Ben Carson, Donald Trump, Jeb Bush and Scott Walker participate in the second presidential debate at the Ronald Reagan Presidential Library in Simi Valley, Calif., on Sept. 16, 2015.(Photo: Max Whittaker, Pool/European Pressphoto Agency)

SIMI VALLEY, Calif.— It's time for the main event.

Eleven Republican candidates gather for the prime-time debate at the Ronald Reagan Library, with insurgent front-runner Donald Trump at center stage.

The New York billionaire is joined by two other self-proclaimed outsiders -- retired neurosurgeon Ben Carson and businesswoman Carly Fiorina — as well as former Florida governor Jeb Bush, Wisconsin Gov. Scott Walker, Texas Sen. Ted Cruz, Florida Sen. Marco Rubio, former Arkansas governor Mike Huckabee, Kentucky Sen. Rand Paul, Ohio Gov. John Kasich, and New Jersey Gov. Chris Christie.

Get ready for the fireworks, and follow our live updates. All times are Eastern.

11:15 p.m.:

That's a wrap! For more debate coverage, check out our full recap.

11:12 p.m.

A final question at the Reagan library debate: How would you change the country in the tradition of Reagan?

Paul and Huckabee say they would create a safer United States.

Rubio predicts allies can count on the United States, and rivals will respect it more.

Cruz pledges to target radical Islamic terrorism, abolish the IRS and repeal Obamacare.

Carson promises "real leadership," better national unity, and rejection of the idea that so many things can be "free."

Trump vows to make the United States "greater than ever before" and other nations will "respect us like never before."

Bush says he can produce higher economic growth, lift people out of poverty and bolster the middle class.

Walker promises to revive Reagan's spirit of optimism and to "fight and win" for America's families.

Fiorina pledges to revive the promises of "Lady Liberty" and "Lady Justice."

Kasich vows to forge "a nation that can solve problems," one that puts country above party.

Christie tells the crowd his presidency won't be "about me — it will be about you."

10:58 p.m.

More levity: What would be your Secret Service code name?

Bush used it to respond to a Trump criticism, saying: "Ever Ready — very high energy, Donald."

Trump's response? "Humble"

10:56 p.m.

What woman would you like to see on the $10 bill?

Paul: Susan B. Anthony

Huckabee: My wife

Rubio: Rosa Parks

Cruz: Take Jackson off the $20 bill and put Parks on

Carson: My mother

Trump: My daughter or Rosa Parks

Bush: Margaret Thatcher

Walker: Clara Barton

Fiorina: I wouldn't change it

Kasich: Mother Teresa

Christie: Abigail Adams

10:50 p.m.

Carson again turns down the chance to attack Trump, this time over the businessman's statements that vaccines may be related to autism.

The retired neurosurgeon says there's no correlation and that he hopes Trump understands because "I just explained it to him."

Trump says autism is a problem and that reducing the pace of vaccinations may help.

Carson disagrees and uses a line that Trump once used on him: "He's an OK doctor."

10:45 p.m.

Climate change is the issue.

Rubio blasts President Obama's climate change proposals, saying they will cripple American businesses and increase utility bills for middle class Americans.

Christie says "massive government intervention" isn't necessary and that government should encourage development of alternative cleaner energy sources.

Chris Christie and John Kasich take part in the presidential debate at the Reagan Library on Sept. 16, 2015. (Photo: Justin Sullivan, Getty Images)

10:40 p.m.

The solvency of Social Security surfaces.

Christie says it's a big issue, and Americans must confront the rising costs of entitlements.

Trump said he and other wealthy Americans should consider giving up Social Security benefits because they don't really need them; Christie calls that a good start.

10:38 p.m.

Gun control is the topic — the Republicans oppose it.

The only people who follow gun laws are law-abiding ones, Rubio says — criminals will simply ignore them.

10:35 p.m.

The candidates take a question posed by CNN Internet users: marijuana legalization.

Paul accuses at least one of his opponents of hypocrisy for backing marijuana laws even though he smoked pot in high school — a claim Bush cops to.

Bush — joking that his mother probably isn't happy with his confession of high school pot smoking — says he wants to rehabilitate drug users, not jail them.

Paul says anti-pot laws fall on poor people and minorities, while "privileged" people like Bush tend to get away.

Paul and Christie also joust over marijuana laws. Paul says the federal government should not interfere with Colorado and other states that have legalized marijuana; Christie says he opposes recreational use.

Fiorina, noting that she lost a child to drug use, says marijuana and other drugs pose real dangers to young people.

10:21 p.m.

Jeb Bush declines to critique his brother's appointment of Chief Justice John Roberts, saying he wants to talk to his criteria for judicial appointments — a proven record of conservative rulings. Bush does say Roberts has made good rulings.

Cruz, for his part, criticizes both presidents Bush over the Supreme Court, the first for appointing liberal Justice David Souter and the second for Roberts.

Bush points out that Cruz publicly supported Roberts' nomination; Cruz called it a mistake.

For his part, Huckabee pledges a conservative "litmus test" for judicial appointees.

10:17 p.m.

Paul opposes U.S. "boots on the ground" against the Islamic State in Iraq and Syria, telling voters "there will always be a Bush or Clinton for you if you want to go back to war in Iraq."

Kasich says he would support boots on the ground against the Islamic State, but only in a coalition with other nations.

10:12 p.m.

Carson says he respects George W. Bush but questioned the rush to war in the wake of 9/11 by saying there are "smart ways to do things" and "muscular ways to do things." He said people need to used their "intellect" to answer challenges.

Christie argues that things were beyond diplomacy after 9/11, and an aggressive response was required.

Rubio also jumps in, telling Carson that "radical terrorism cannot be solved by intellect."

10:04 p.m.

Bush acknowledges he would likely hire advisers who worked for his father and brother when they were presidents, but quickly added "I'm my own man."

Trump, meanwhile, criticizes George W. Bush over the Iraq war, calling his presidency a disaster that paved the way for Barack Obama.

Defending his brother, Jeb says of George: "He kept us safe."

When Trump counters that "I don't feel safe," Bush and others blame that on Obama.

Paul also criticizes Bush and his brother over Iraq; Jeb Bush says many of the problems in Iraq resulted from Obama's premature pullout.

Mike Huckabee and Marco Rubio take part in the presidential debate at the Reagan library on Sept. 16, 2015 in Simi Valley, Calif. (Photo: Justin Sullivan, Getty Images)

9:57 p.m.

More Trump bashing, this time by Rubio over national security.

Rubio says the next president needs to understand the dangers facing the world, and he suggested that Trump does not.

Trump says he will protect national security by hiring the "best people" and that "the world is a mess" — and pointed out all the votes Rubio has missed

9:48 p.m.

Fiorina unleashes a huge attack on another opponent — Democrat Hillary Clinton — and says the former secretary of State cannot defend her record on emails or Benghazi.

Kasich says he's just as soon not attack his opponents — Republicans or Democrats like Clinton — but talk about his own record instead. "People still have to get to know me," the Ohio governor says.

9:43 p.m.

The candidates debate the best approach to taxation.

Huckabee disputes proposals by Trump and Bush to increase the taxes of hedge fund managers, asking "why should we penalize productivity?" He called for a "fair tax" based on consumption.

Carson pitches a flat tax but declines an invitation to criticize Trump over his support for a progressive tax code.

Trump says flat taxes favor the wealthy, who should be levied at a higher rate.

Paul says a flatter tax would help the middle class, while Walker hails the Reagan-era tax cuts.

Republican presidential candidate businessman Donald Trump speaks during the Republican presidential debate at the Reagan library on Sept. 16, 2015. (Photo: Mark J. Terrill, AP)

9:35 p.m.

Trump and Fiorina argue about who has the better business experience.

Trump attacked Fiorina's tenure as CEO of Hewlett-Packard, calling it a "disaster," and adding that "she can't run any of my companies."

Fiorina cited Trump's four bankruptcies and said his companies ran up big debts with other people's money.

She defended her dismissal as CEO of Hewlett-Packard, saying she led the company through difficult times and fell victim to "enemies" who defended the status quo.

Christie, meanwhile, criticized the "childish back-and-forth" between his two opponents, and said they should be talking about the "middle class that's getting plowed over."

9:28 p.m.

The candidates debate "birthright citizenship."

Trump says the children of non-documented people should not automatically be granted citizenship; Fiorina says birthright citizenship is guaranteed by the Constitution and blamed the Democrats for not fixing the immigration system overall.

When Trump questioned the constitutionality of birthright citizenship, Fiorina shot back: "Not every one agrees with you."

9:25 p.m.

Another frequent Republican fight: what constitutes "amnesty" for migrants who are in the U.S. illegally.

Cruz basically says any kind path to any kind of legal status — ideas endorsed by Bush, Rubio and Carson, among others — amount to amnesty.

Rubio says the first priority is to secure the border, but the legal immigration system needs to be modernized. Carson says the U.S. should have a guest-worker program

9:20 p.m.

Trump defends his plans to build a wall along the nation's Southern border in order to keep out migrants from Mexico and to deport the 11 million migrants who are already here.

Opponents are skeptical.

Christie calls Trump's plans impractical, while Bush said they would cost hundreds of billions of dollars and break up too many law-abiding families.

Bush also called on Trump to apologize for a Twitter crack about Bush's Mexican-born wife. Trump called Bush's wife a lovely person and added that he said nothing wrong.

Trump, meanwhile, knocked Bush for occasionally speaking Spanish; Bush said he would continue to do so if people speak to him in Spanish. Rubio, the son of Cuban migrants, also spoke on behalf of Spanish speakers.

9:08 p.m.

Topic: Trump's recent comments about Fiorina's face.

Fiorina, the only woman on the stage, said, every woman heard Trump's comment "very clearly," and that it was obviously about looks.

Trump said Fiorina has a "beautiful face" and is a "beautiful woman.

9:06 p.m.

The candidates support defunding Planned Parenthood over its abortion policies but disagree over how to go about it.

Kasich supports it, but says the issue isn't worth shutting down the government; Cruz says congressional Republicans should do whatever it can to eliminate federal funding for Planned Parenthood because of its abortion policies.

An impassioned Fiorina — the only woman on the stage — said the Republican Congress should at least force President Obama to veto a budget that eliminates Planned Parenthood funding, saying "this is about the character of our nation."

Walker says the failure to zero out Planned Parenthood is another reason Republicans don't like their members of Congress.

Republican presidential candidate Carly Fiorina, right, speaks as Scott Walker looks on during the CNN Republican presidential debate. (Photo: Mark J. Terrill, AP)

8:55 p.m.

Huckabee defends his defense of the Kentucky county clerk who refused to issue marriage licenses to gay couples, saying she is entitled to practice religious liberty and resist "judicial tyranny."

Bush says that while he disagrees with the Supreme Court decision on gay marriage, public officials must obey it.

8:52 p.m.

Kasich again clashes with Cruz over the Iran nuclear deal.

Kasich says the U.S. can re-sanction or even attack Iran if it cheats the agreement and seeks a nuclear agreement; Cruz says the deal makes it impossible to learn if Iran is cheating.

8:50 p.m.

Foreign affairs continues to dominate the debate, with a question about Syrian refugees.

Trump, Rubio and Cruz blame President Obama for the crisis out of Syria (and Iran, for that matter). "Quite frankly, people don't trust this president," Rubio said.

8:46 p.m.

Huckabee, who protests being left out of the debate so far, assails the Iran deal.

8:45 p.m.

China also provokes a dispute between the candidates.

Walker says President Obama should cancel next week's state dinner with the leader of China; Paul and Bush say no, arguing that a president has to talk with rivals, especially one as important to China.

8:42 p.m.

Cruz and Kasich argue about the Iran nuclear deal.

Cruz calls the agreement "catastrophic" and says he will rip it to "shreds" if he is president.

Kasich agrees that the Iran deal is a bad one, but the next president has to pursue it and make sure that Iran lives up to the bargain — and be prepared to retaliate if the Iranians move to a nuclear weapon.

Republican presidential candidates participate in the second primary debate at the Reagan library in Simi Valley, Calif., on Sept. 16, 2015. (Photo: Max Whittaker, Pool/European Pressphoto Agency)

8:39 p.m.

The subject of Vladimir Putin comes up.

Trump says Putin will respect him, unlike the way he has disrespected President Obama.

Rubio outlines Russian behavior in Ukraine and Syria, and said he will confront Putin over it.

Fiorina says we've talked about enough Putin; we should build up our military, and "Vladimir Putin will get the message." She also refers to Trump's recent failure to identify a key Iranian official.

8:35 p.m.

Bush and Trump mix it up over ... casino gambling in Florida, which Bush helped block.

"Yes, you did — you wanted it," Bush told Trump, who denied it.

"I promise, if I wanted it, I would have gotten it," Trump said.

Trump also repeated his claim that Bush would be a puppet of his political donors; Bush says Trump is being less than honest about his past support for Democrats.

8:30 p.m.

The issue of outsiders-vs.-the-establishment surfaces.

Christie says he's also an outsider — "a Republican (governor) in New Jersey."

Carson, one of the self-described outsiders, says career politicians are too often expedient while the country heads in the wrong direction. He declines to identify bad politicians by name.

Fiorina, who has also never held public office, says people believe current politicians have failed them. "This is about changing the system," she says.

8:27 p.m.

Not surprisingly, the first question is about Trump (who mugs for the camera as candidates are asked if he is qualified to be president.)

Fiorina calls Trump a "wonderful entertainer," but is not presidential material.

Trump, following form, first says the low-rated Paul — another Trump critic — doesn't even belong on the stage. Also says he has the business experience and temperament to be president.

Paul hits Trump for a "sophomoric quality" to his attacks on people's looks and personality.

Trump assails one of the earlier debaters — Pataki — as a failed governor.

Bush, invited to critique Trump, says it's up to the voters to judge him, but says he can't be rude to foreign leaders.

Walker also jumps into the bash Trump-fest, saying the nation doesn't need another "apprentice" in the Oval Office because have one already; Trump responds by attacking Walker's record as governor of Wisconsin, and notes his drop in the polls.

Kasich, meanwhile, criticizes the entire line of questioning, saying the issues are more important than Trump.

8:19 p.m.

And we're (finally) off ... The candidates are asked to introduce themselves.

Paul says he spends his days defending the Constitution and the Bill of Rights.

Huckabee says there are no socialists in the field, and nobody is under investigation; calls the Republicans "the A Team."

Rubio praises Ronald Reagan's legacy — and jokes about his water drinking habits, playing off the Californian drought.

Cruz says he will "stand up to career politicians in both parties."

Carson says he's very concerned about the direction of the country and our children's futures; welcomes Fiorina to the prime stage.

Trump notes he wrote the The Art of the Deal and wants to bring his business talents to the White House.

Bush describes himself as a "committed conservative reformer."

Walker says Ronald Reagan liked to go "big and bold" — which just happens to be his own campaign slogan.

Fiorina says the government has grown too big and powerful — and too "inept" and "corrupt."

Kasich notes he actually flew the Air Force One airplane that provides the stage backdrop.

Christie asks the audience whether they believe their children are better off under President Obama — no one in the Republican crowd says yes.

8:04 p.m.

The candidates walk to the stage to applause, and pose for pictures.

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