CNN

A new poll handicaps Arlen Specter's general election chances in 2010 against two prominent Pennsylvania Republicans.

WASHINGTON (CNN) – The White House restated its support for Republican-turned-Democratic Sen. Arlen Specter on Tuesday despite his vote against its budget and a threatened primary challenge.

"I think the president was pretty clear on this," White House spokesman Robert Gibbs said. "Senator Specter has his full support and he'll do what's necessary to see him re-elected."

Specter, of Pennsylvania, jumped parties last week in a move that could give Democrats a filibuster-proof supermajority in the Senate. But Rep. Joe Sestak, who had been considering a Senate run before Specter's decision, has questioned party leaders' acceptance of the five-term senator.

Specter quit the GOP ahead of a primary challenge in that party that he admits he was likely to lose. Though his support for President Barack Obama's nearly $800 billion economic stimulus plan angered conservative Republicans, his first vote was to oppose Obama's upcoming budget.

Gibbs said the administration doesn't "generally get 100 percent of any party voting for us, but we'll continue to try."

Sestak, a former admiral who now represents a portion of the Philadelphia suburbs, told CNN that party leaders' support for Specter was "understandable but short-sighted."

"I think that's Arlen's responsibility to act how he thinks is right," Sestak said. "It's our responsibility as Pennsylvanians to judge those actions."