What’s so striking about this year’s huge field of Republican candidates is that so few of them appear to be plausible nominees, broadly acceptable across the party. With Scott Walker now out of the race, the short list of such candidates got even shorter.

Considered one of the favorites to win the nomination, he was as recently as last month second in the betting markets to Jeb Bush. And yet, his campaign lasted just 70 days.

In a way, his decision to withdraw is good for the party. It hastens the process of winnowing the field, and it may bring many party elites closer to deciding on a candidate. It might help Marco Rubio in particular. Mr. Walker’s decision to drop out also highlights the difficulty of maintaining a broad coalition in a party deeply divided between conservatives and moderates, populists and business interests, the grass-roots and the elites.

No candidate seemed better positioned to overcome those divisions than Mr. Walker. He became a conservative hero when, as governor of Wisconsin, he prevailed against organized labor in a high-profile battle over collective bargaining rights. He had irreproachable conservative credentials. He was also a favorite of much of the party’s elite — including the Koch brothers. He was the fighter conservative with goals that were palatable to party elites.

Mr. Walker faltered so quickly because he simply was not skilled enough to navigate the competing pressures of appealing to the party’s establishment at the same time as arousing its base. It was much like the story of Rick Perry.

Though the entry of Donald Trump into the race made things harder for all the Republican candidates, Mr. Trump can’t be blamed entirely for Walker’s troubles. Mr. Walker was tied with Mr. Bush for second place in national polls heading into the first debate, long after Mr. Trump took a lead in those polls. By the time he dropped out, Mr. Walker had the support of less than one-half of 1 percent of Republican primary voters, according to the most recent CNN survey.

The Walker campaign — or perhaps the candidate personally — felt pressure from the rise of Mr. Trump on his right, especially once Mr. Walker started slipping a bit in the polls. This sort of pressure isn’t unusual and was inevitable — he would have felt it at some point, if not from Mr. Trump, then from Ben Carson or Ted Cruz.

Mr. Walker, to put it gently, did not handle this pressure well. His instinct was to move to the right as fast as possible at any point of vulnerability. He staked out a conservative position on birthright citizenship and a fringe position on considering a wall at the Canadian border. These moves alienated party elites and weren’t credible to conservative voters. He quickly reversed positions; in the end, he reassured no one.

The exit of Mr. Walker could be good news for party elites. A narrower field increases the odds that the party will reach a decision. But the party’s mainstream alternatives — Mr. Bush, John Kasich and Mr. Rubio — have not yet shown the ability to connect broadly with G.O.P. primary voters. Mr. Bush simply hasn’t been a strong campaigner; “low-energy,” one might even say. Mr. Kasich may be too moderate to win the nomination.

Of those three, Mr. Rubio may be the biggest beneficiary. He is the most reliably conservative of the three mainstream candidates, so it seems possible that establishment conservatives will accept him.

His chances of winning the nomination have improved over the last three months. Back in April, he seemed to be blocked by Mr. Walker and anti-establishment candidates on the right. Mr. Bush held the center, the party’s relatively moderate elite. Mr. Rubio was broadly acceptable, but no faction’s first choice.

It wouldn’t be surprising if Mr. Rubio now picked up elite support from Mr. Walker. Whether he is strong enough to capitalize on this gift is an open question.