“Those decisions will be made by people in the state, and our members in the state know who will stand with them,” Trumka said on the ABC News daily webcast “Top Line.” “And if Arlen Specter — he stood with them in the past — if he continues to stand with them, they’ll support him. If he doesn’t, they won’t support him.”

“There will be opposition to Specter in the Democratic ranks,” said Pennsylvania GOP political analyst Charlie Gerow. “It was believed that the governor would be able to muscle out the Democratic opposition, and that hasn’t taken place.”

Toomey hasn’t exactly caught the fancy of his party, either. Almost as soon the reality sunk in that the conservative former three-term congressman could be the GOP nominee in Democratic-trending Pennsylvania, some Republicans began casting about for an alternative.

“I don’t think there is anybody in the world who believes he can get elected senator there,” Utah Sen. Orrin Hatch, the vice chairman of the National Republican Senatorial Committee, said last week.

POLITICO reported Thursday that the National Republican Senatorial Committee was in contact with moderate Pennsylvania Rep. Jim Gerlach. On Saturday, Roll Call reported that national and state Republicans were urging another moderate, former GOP Gov. Tom Ridge, to join the race.

“The irony, of course, is that Republicans are looking for that moderate candidate who can beat Toomey and hold the seat, which, if that is the case, makes Arlen Specter’s argument,” said Pennsylvania Democratic consultant Larry Ceisler. “They bought the message but not the messenger.”

In the first public poll taken since Specter’s party switch, the five-term incumbent leads Toomey in a prospective matchup by 20 points, 53 percent to 33 percent.

The Quinnipiac University survey shows Ridge would be a formidable opponent against Specter and shows Specter leading the former governor by only 3 points, 46 percent to 43 percent.

NRSC Chairman John Cornyn of Texas hesitated when given the opportunity to endorse Toomey on Friday.

“I don’t think it’s wise for me to tell Pennsylvania Republicans who their nominee should be, so I’m not going to do that,” said Cornyn. “But we want to make sure the strongest nominee is chosen so we can run them against whoever wins the Democratic nomination. Our goal is to hold onto that seat, and we’ll do whatever we can to make it happen.”