Video: Obama, Biden, Specter Speak

WASHINGTON - President Barack Obama on Wednesday hailed Arlen Specter's conversion to the Democratic Party, while Specter vowed that he'll be an asset as Obama tries to get his ambitious agenda through Congress.

Obama said, "I am grateful that he is here."

Specter was joined by Obama and Vice President Joe Biden at the White House Wednesday morning. Specter noted that he and longtime friend Biden "have talked over every problem under the sun and the moon."

With a beaming Obama standing at his side, Specter said: "I think that I can be of assistance to you, Mr. President. ... There are a lot of big issues we're tackling now that I've been deeply involved in."

Obama praised Specter for his work on health care, education, expanding America's manufacturing base and medical research. Pointing out that Specter has battled multiple life-threatening diseases, Obama called the senator "one tough hombre."

"I don't expect Arlen to be a rubber stamp," Obama said. "In fact, I'd like to think that Arlen's decision reflects recognition that this administration is open to many different ideas and many different points of view."

The president added, "I'm eager to receive his counsel and his advice, especially when he disagrees."

Biden said, "I'm even more pleased that Arlen's independence, integrity and purist intellect will now be sitting in the Democratic caucus."

For years, Biden has encouraged his friend Specter, a moderate Republican, to join the Democratic Party. Specter finally saw it Biden's way, announcing Tuesday that he was leaving the GOP in a move that put Obama's party to within one vote of the 60 needed to overcome Senate filibusters.

Democrats inside and outside the White House insisted that Specter made the decision on his own and without pressure from Obama's inner or outer circle. The White House says it didn't promise Specter anything, such as a plum committee assignment or a clear Democratic primary field.

Democratic officials privately credited Biden, the former Delaware senator who is close to Specter both personally and professionally, and his persistent prodding through the years with helping create a comfortable, welcoming environment for the five-term Pennsylvania senator to make the change.

"I have been working on that in earnest for the past four years and double time for the past 100 days (as vice president)," Biden told a Democratic fundraiser in Houston on Tuesday.

Specter and Biden served together for many years on the Senate Judiciary Committee and are from neighboring states.

In February, in Philadelphia, Biden thanked Specter for being one of only three Republicans to support Obama's economic stimulus bill and said, "In his heart, I know he's a Democrat."

One senior White House official, who spoke on the condition of anonymity because discussions were private, said Biden and Specter have talked in person or by phone once a week since Obama was sworn into office but switching parties didn't always come up. The official said Biden did not find out that Specter was leaving the GOP until the senator told the vice president Tuesday morning.

Another senior White House official said Obama was surprised to learn of Specter's decision. The official said Specter's switch was not the product of a long negotiation with the White House and was not part of a quid pro quo in which Obama officials brokered a deal of any sort.

Even so, advisers swiftly pledged to swing the weight of the White House behind Specter's re-election bid, promising to work on his behalf in a Democratic primary if Specter asks.

"If the president is asked to raise money for Sen. Specter, we're happy to do it," press secretary Robert Gibbs said. "If the president is asked to campaign for Sen. Specter, we'll be happy to do it."

He added: "I think the president is quite pleased. Understatement of the day."

Republican Senate candidate former Congressman Pat Toomey said the news conference wasn't a surprise. He said it's to be expected that Specter is getting support from the president since he's backing a Democratic agenda.

Toomey said the most notable fact is Specter's amazing betrayal of his party of 30 years. He visited "Good Day Philadelphia" on Wednesday to discuss the veteran lawmaker's decision.