The wish list among Republicans is wide and varied. Sarah Palin, a former governor of Alaska, retains a devoted following. But activists also express a longing for others to step off the sidelines, including Gov. Chris Christie of New Jersey, Gov. Rick Perry of Texas and Representative Paul D. Ryan of Wisconsin, the chairman of the Budget Committee.

The first debate of the nominating contest is Thursday on Fox News, and party officials believe that the presidential field will be all but set by June, giving urgency to the call for more candidates.

Photo

Parties facing an incumbent president often have trouble establishing the stature of their candidates in the early going. But the challenge for Republicans this time is especially striking given Mr. Obama’s vulnerabilities and the passion of the grass-roots conservative movement that helped propel the party to big gains in Congress and statehouses in 2010.

The party lacks the establishment-anointed candidate that has led it into every presidential cycle for decades. Mitt Romney, a former Massachusetts governor, may come closest to that role, but he has kept a relatively low profile to avoid becoming a target. Newt Gingrich, a former House speaker, is well known but has political and personal liabilities. Newer faces like former Gov. Tim Pawlenty of Minnesota are barely known to most voters.

There is no guarantee that any Republicans on the sidelines would energize the party, but they seem to be getting almost as much attention as those clearly in the race. Reince Priebus, the Republican National Committee chairman, said last week that the race was still unformed and that he expected others to join.

The loudest and most persistent entreaties are directed toward Mr. Daniels, who for two terms as governor has shown that fiscal conservatism and political popularity can go hand in hand.

Mr. Daniels, who says Republicans should be more focused on addressing the country’s fiscal condition, worked in the Reagan administration and as budget director for President George W. Bush. An alumni network of those administrations, ranging from top contributors to field operatives, has elevated a whisper campaign into a forceful effort to enlist him.

Advertisement Continue reading the main story

The decision last week by another establishment favorite, Gov. Haley Barbour of Mississippi, not to pursue a presidential bid has increased pressure on Mr. Daniels, who drew national attention on Friday for saying he would sign a bill that cuts off Medicaid financing for Planned Parenthood in Indiana. His allies have started mapping out a campaign structure that could be fully in place this month, including a campaign headquarters in downtown Indianapolis.

“What sets Mitch apart from the other candidates who are currently running, he is very, very direct and very open about what needs to be done,” said Al Hubbard, a director of the National Economic Council. “I’m disappointed that the other candidates who are currently talking about running are reluctant to do that.”

The call for new candidates, which was the topic of some conversation here Friday at a Republican dinner, is hardly universal. Some Republicans point to the 1992 Democratic field, initially derided as uninspiring, which produced President Bill Clinton.

Photo

But there has been an undercurrent of concern in the party for months. The conservative columnist Charles Krauthammer called the field “split and weak” two weeks ago on Fox News.

Peter Wehner, a former adviser to Mr. Bush, credited a “lack of fizz” in the field so far with letting Mr. Trump gain attention as a potential Republican candidate despite previous contributions to Democrats and even a suggestion for the nation to examine a single-payer health care system.

“At this point, there appears to be a flatness to the field,” said Mr. Wehner, who has been highly critical of Mr. Trump. “There’s a void right now, and even clowns can fill voids.”

Newsletter Sign Up Continue reading the main story Please verify you're not a robot by clicking the box. Invalid email address. Please re-enter. You must select a newsletter to subscribe to. Sign Up You will receive emails containing news content , updates and promotions from The New York Times. You may opt-out at any time. You agree to receive occasional updates and special offers for The New York Times's products and services. Thank you for subscribing. An error has occurred. Please try again later. View all New York Times newsletters.

In interviews, Republican governors, state party leaders and prominent activists urged the candidates to engage more directly.

“We’ve lost enough time — let’s start talking about the issues that matter to the people of this country,” Gov. Nikki Haley of South Carolina said. “I think they’re all waiting for ‘go time,’ but the people of South Carolina are saying ‘go.’ Let’s start hearing about the issues.”

Mr. Pawlenty, who was among the first in the race, said candidates had plenty of time to excite voters. He said a fierce opposition to Mr. Obama would unify Republicans and strengthen the field, adding, “The faster, the sooner, the more aggressive we can do that, the better.”

Advertisement Continue reading the main story

As of late last week, it was still unclear how many potential candidates would show up for Thursday’s debate. Mr. Pawlenty, who will attend, was urging more of his potential rivals to join him.

While some Republicans have expressed impatience to get the race started in time to raise ample campaign financing, veterans of races past said the money would flow when the field finally settles.

“Hardly anybody’s declared yet, so who are you going to rally around?” said Fred V. Malek, an investor and longtime Republican fund-raiser, who added that he was not concerned about the slow start. “Contributors are waiting until the field is fully formed.”