Mr. Romney has been by far the most assertive, according to interviews with a half-dozen top Republican fund-raisers, already pushing for commitments from major donors should he formally decide to run.

Over the summer, Mr. Romney, the former Massachusetts governor, invited top bundlers of campaign checks from key states to his vacation home in New Hampshire on several occasions to help firm up their commitments. Mr. Romney has already lined up an array of prominent supporters, including a billionaire, David Koch, who has donated heavily to conservative causes over the years, and Robert Wood Johnson IV, the billionaire owner of the New York Jets and one of the party’s most coveted fund-raisers.

Mr. Pawlenty has also been putting together a financial apparatus. On Monday and Tuesday evening, for instance, he met with top fund-raisers who flew to Minneapolis to listen to a briefing on his record as governor. Those were the latest in a series of such meetings that began in September, according to William Strong, a vice chairman at Morgan Stanley who has spearheaded fund-raising for Mr. Pawlenty’s political action committee, Freedom First…

There have been some notable occasions where Ms. Palin has also engaged in the kind of glad-handing with major donors that typically precedes a presidential run. In early October, for example, she had dinner with a contingent of prominent Republican donors, political figures and others in West Palm Beach, Fla., for an event organized by Christopher Ruddy, head of the conservative magazine and Web site Newsmax.