“A number of people just volunteered that they were going to do their part in L.A. or San Diego or Palm Beach or Philadelphia or New York,” Mr. Wynn said. “Without being asked, they said, ‘We can do it.’ ”

Mr. Perry’s strength as a fund-raiser reflects, in large part, his tenure as governor — he is the longest-serving chief executive in Texas history — in a state that is a treasure trove of Republican money and has few restrictions on political giving. And as a sitting governor, he has one advantage that the Republican field’s current top fund-raiser — Mr. Romney, a former Massachusetts governor — no longer enjoys.

In Texas, individuals and political action committees can give unlimited contributions to candidates for governor, and Mr. Perry has exploited that to the hilt: according to a study by Texans for Public Justice, half of Mr. Perry’s campaign contributions, roughly $51 million in the last decade, have come from 204 donors giving $100,000 or more. One couple, Robert Perry, a Texas homebuilder, and his wife, Doylene, who are not related to the governor, have given Mr. Perry more than $2.5 million over the years.

In a state whose government is fragmented among dozens of commissions, boards and agencies, Mr. Perry has also raised donations aggressively from his own appointees, an approach permitted by state law and practiced by governors of both parties. According to Texans for Public Justice, since taking office in late 2000, Mr. Perry has raised more than $17 million from 921 of his appointees or their spouses.

“Democrats and Republicans have traditionally done this,” Mr. McDonald said. “But he’s taken it to a higher level than anyone else.”

In part because federal law caps at $2,500 the amount individuals can give to any one candidate during the primaries, Mr. Perry will not be able to raise money nearly as easily as he has in the past. But his top donors represent a corps of bundlers that any of his rivals would envy.

And thanks to loose campaign rules in the wake of the Supreme Court’s Citizens United decision, whatever money his wealthiest Texas supporters cannot give directly to Mr. Perry could easily end up in the coffers of one of the half-dozen or so “Super PACs” — technically independent groups that in the wake of the court decision can raise and spend unlimited amounts of money to support a candidate — that have been set up in recent weeks by supporters and former Perry aides.