The candidates’ spouses, Ann Romney and Carol Paul, “know each other better than any of the other wives,” Mr. Paul said. He and Mr. Romney talk “all the time” and “we’ve met all their kids.” Once he telephoned Mr. Romney just as Mr. Romney was calling him. “Sometimes I’m never sure who issued a call,” he said.

Mr. Paul has already provided some tactical help: When Mr. Romney began to flounder in South Carolina and was under attack over his career in leveraged buyouts, Mr. Paul came to his defense, suggesting that his critics were anticapitalist. His campaign even issued a press release assailing other rivals for, in Mr. Paul’s view, taking Mr. Romney’s quote about firing people out of context.

What is not clear is how much, and under what circumstances, Mr. Paul might ever provide any more tangible help to Mr. Romney. His aides say publicly that Mr. Paul is committed to winning the nomination. And the two camps are at odds right now over the outcome of last weekend’s Maine caucuses, in which state Republican Party officials declared Mr. Romney the winner by a relatively small margin over Mr. Paul even though some places have yet to cast ballots.

Short of the nomination, Paul aides say, the Texan wants to influence the party, the platform and its nominee on a range of issues, like scaling back the Patriot Act and bringing more scrutiny to the Federal Reserve. But it is unclear how far any nominee might go toward meeting Mr. Paul halfway. A number of his positions, like ending foreign wars, are anathema to establishment Republicans.

In the meantime, Mr. Paul has slowly been collecting delegates, and is now threatening Mr. Gingrich for third place on that front. And his supporters plan to pack state party conventions to grab more delegates in states like Iowa, Maine and Minnesota, which will probably give Mr. Paul more leverage as the nominating battle progresses.

There are also Mr. Paul’s formidable financial resources, which he can deploy as the other candidates struggle to raise money for an extended nominating fight. Jesse Benton, his national campaign chairman, said the campaign was on track to collect more than $10 million in the first quarter of 2012, in daily amounts of $30,000 to $50,000 augmented by occasional “money bombs.” That is less than the $13 million raised in the fourth quarter but more than the $8 million in the third quarter.

Mr. Paul’s feelings for some other candidates who have competed this election season are more complicated. He served in the House when Mr. Gingrich was speaker in the late 1990s, but they never had a particularly close relationship. “Personally, it’s never been bad, with cross words, but he’s never been supportive of my campaign efforts when I ran for office,” Mr. Paul said. “But I never took it personally.”