Toomey has redoubled efforts to court skeptics in the party establishment in the two weeks since former Gov. Tom Ridge declined to enter the race for the GOP nomination despite the pleadings of prominent moderates.

Five-term Sen. Arlen Specter defected to the Democrats April 28, in large part because he concluded that he could not defeat Toomey again in a GOP primary, a move that scrambled the 2010 race. But some Republicans believed that Toomey, a former U.S. representative from the Lehigh Valley, would have difficulty winning the general election in a state that has trended Democratic in recent years.

"In those days after Arlen switched, there was panic on the Republican side, and that has dissipated a bit," said William Green, a GOP political analyst in Pittsburgh. "People meet Pat, and they see that he's not a fire-breathing dragon. . . . He's an economic, Jack Kemp conservative."

Toomey most recently headed the Club for Growth, an activist group that has earned some enemies by targeting and unseating moderate Republicans.

State GOP chairman Rob Gleason, one of those who encouraged Ridge to run, said he was no longer "actively recruiting" other candidates and believed Toomey could win a general election.

It's only natural for talk of Toomey's vulnerability to fade as Republicans grow more comfortable with the idea of him as their standard-bearer, Gleason said.

"There's nobody out there who's an alternative, so why would you say that the guy is unelectable when he's it - the likely nominee?" Gleason said. "He has 18 months to win over a majority of the people in Pennsylvania."

Toomey and the GOP in general will be helped by growing concerns over the level of government spending under the Democrats nationally, Gleason predicted.

Rep. Jim Gerlach (R., Pa.) is still considering running for the Senate, an adviser said, but he has been more focused on an exploratory campaign for governor. Johnstown GOP activist Peg Luksik has declared her Senate candidacy but is considered a long shot.

"I think we've gone a long way toward uniting the party behind my candidacy," Toomey said in an interview Friday. "That job is not finished yet. . . . Many of the folks who were not on my side didn't get a chance to get to know me."

Toomey came within 17,000 votes, out of more than one million cast, of defeating Specter in the 2004 primary.

Toomey and his supporters are touting his three straight wins, from 1998 to 2002, in the Democratic-leaning 15th Congressional District, which includes part of Montgomery County, and point to encouraging polling data. Those polls show Specter capturing barely half the voters in a general-election matchup and the lesser-known Toomey within striking distance.

On May 14, Toomey won an endorsement from moderate Republican Rep. Charles W. Dent, his successor in the House.

"Pat is the presumptive nominee," Dent said on a talk show on Allentown's WAEB-AM. "I think he's going to be able to pull the Republican Party together. He's going to be able to unite people of different ideological persuasions."

And in an op-ed piece in the Pittsburgh Post-Gazette and other newspapers this month, Toomey outlined a vision of a Republican Party with room for vigorous debate around the "unifying idea" of individual freedom and limited government.

Though he opposes abortion rights, Toomey wrote, "I would certainly not suggest that those who disagree with the pro-life position be banished from the Republican tent."