Losing hope that their Iowa brethren will coalesce around a suitably like-minded candidate in Tuesday’s Republican caucuses, national conservative leaders are beginning to accept the increasingly likely prospect of a Mitt Romney nomination, and how and whether they can live with that.

“The answer to that, to a large extent, totally rests with Romney,” said Richard A. Viguerie, a direct-mail pioneer and longtime leader of the conservative movement . “The first half-dozen moves are his. We’re just tired of supporting the Republican establishment candidates and getting nothing but lip service in return. Those days are over with.”

Viguerie said his hope is that if Romney wins the nomination, he makes a strong effort to win over conservatives, and the most critical step he can take is to select an appealing running mate.

“Romney’s got a big hill to climb to get conservatives enthusiastically on board,” he said. “I don’t know if he is capable of doing that. He needs tens of thousands of conservatives and tea parties and bloggers and organizations singing that song.”

The dismay among conservatives about Iowa rests largely on the reality that, despite their overwhelming majority among Republican caucus-goers, they have split their support between five candidates: Rep. Ron Paul of Texas, former Pennsylvania senator Rick Santorum, former House speaker Newt Gingrich, Texas Gov. Rick Perry and Rep. Michele Bachmann of Minnesota.

Meanwhile, Romney, the former Massachusetts governor whom they have resisted out of concern that he is too moderate, is in position to win the caucuses, even though about three-quarters of the vote will probably go to someone else.

The other candidates and their supporters continued making the case Sunday for voters to rally around a single conservative to block Romney’s nomination. But to many, the prospects appeared dim.

Pastor Dan Berry of the Cornerstone Family Church in Des Moines said after services Sunday that several candidates appeal to conservative Christians — and a number had sought his endorsement. He declined, he said, in part because so many of the candidates are appealing — including Romney.

The splintering is in sharp contrast with 2008, when former Arkansas governor Mike Huckabee rallied conservative voters to win the caucuses.

“Four years ago, people had their minds made up early,” Berry said. “It was easy for a lot of the Christian conservatives to make their decision earlier. That’s not the way it’s happening this time, with all the ups and downs, it’s been harder to choose. They all have strengths. Most people think the Christian conservative is only concerned about the social part of it. We’re all concerned about life and marriage, but also the economy.”

Santorum compared the difference between 2008 and this year to ordering at his favorite cheesesteak shop in Pennsylvania. “You ever been to Geno’s in Philadelphia?” he asked on the trail last week. “How long does it take you to order at Geno’s? You know what they sell? Cheesesteaks. That’s it. It’s pretty simple to order. Go to a menu where you’ve got three or four pages of menu and it’s going to take you longer to order. In 2008, you had a Geno’s election. Mike was the cheesesteak. . . . He was it.”

Gingrich, campaigning at a sports pub in Marshalltown on Sunday, said the potential for conservatives to rally around one candidate does not end in Iowa.

“It’s pretty clear from the Des Moines Register poll that conservatives who want real change are going to get probably between 70 and 75 percent of the vote, and the only moderate establishment candidate is going to get about 20 or 25 percent of the vote despite massive spending for two consecutive races,” Gingrich said. “And I think that’s going to set the stage for the whole rest of the campaign.”

He added: “It’s going to be overwhelming that the conservative base of the party is still there, and that Governor Romney remains a Massachusetts moderate and has not broken out despite spending millions of dollars. As we go on to New Hampshire, South Carolina, Florida and beyond, those numbers will ultimately prove decisive in the race.”

Campaigning on Sunday in Atlantic, Iowa, Romney was asked about his outreach to social conservatives. He said that his goal in Iowa is to be seen as the candidate capable of winning, which means building support and organization in other states.

“It’s been important to me,” he said, “to make sure that I have a team and a capability to go the full distance, to get the nomination and to have the people in Iowa who caucused for me be proud that they were on that team from the very beginning.”

Some conservatives are less certain that there is any chance of stopping Romney after Iowa. One national conservative leader, who requested anonymity to speak freely, said he and other conservatives were in talks as recently as the past month about whether it was still possible to draw in another candidate who could consolidate the vote — someone like Louisiana Gov. Bobby Jindal. But time is short for that, the leader said. “You have a number of people who are good candidates, but none just leaps out at you, so where do people land?” he asked.

Several people interviewed at Cornerstone Family Church on Sunday said they were looking for the candidate who best represented their Christian values. Some said Romney wasn’t ideal, but they could accept him as the nominee if necessary to beat President Obama.

“My gut feeling is it’s going to end up being Romney. He won’t be my first choice. Or my second choice. But I’ll support him if it comes to that,” said Mike Carolus, 59, a mechanic from Des Moines, who said he’d prefer Perry or Bachmann.

“The way I feel about this election is, you can go down through every single one of them, and if you’re looking for Mr. or Mrs. Perfect, you’re not going to find it,” said Dan Brown, a trader from Des Moines who said he’d be willing to support the candidate he calls “the plastic man” because of his background in business. “My number one agenda is to get Obama out of there. After that, I’ll look at the issues.”

Staff writer Philip Rucker contributed to this report.