Sen. Arlen Specter (Pa.) was warmly welcomed to the White House on Wednesday morning by President Barack Obama and Vice President Joseph Biden as the three sealed his arrival in the Democratic Party with an appearance before the cameras. Biden offered a particularly hearty embrace, noting his personal ties to Specter that included family visits and countless rides together along Amtrak’s Northeast Corridor line from Washington to their home states of Delaware and Pennsylvania. “Arlen Specter has been my friend and confidant and in scores and scores of pieces of legislation and issues,— Biden said. “He’s been there when things have been tough for me, and I hope I’ve been there for him.—Obama and Specter appeared to allude to a role for Biden in convincing Specter to defect from the GOP, with Specter thanking Biden for his “encouragement— and Obama pointing to a possible Amtrak conversion. “I’m grateful that [Specter is] here, but I’m also grateful that Joe Biden paid him a little attention on the train,— Obama said.Obama reiterated that he and Biden plan to back Specter in a Pennsylvania Democratic Senate primary and said he is “confident— Specter will win re-election. Both the president and Biden nodded toward Specter’s well-known independence, with Obama saying Specter will not “rubber-stamp— his agenda. “I don’t expect that Sen. Specter will agree with every decision I make,— Obama said.Specter said he was “comfortable— with his decision and with Obama’s administration. He acknowledged that informing his Republican colleagues of his decision was “not an easy conversation.— Obama suggested Specter even gave him a little political advice on how to win in Pennsylvania, though it was unclear the extent of it and whether Obama was referring to the contest in the primaries or the general election.Obama also used the occasion to address the growing swine flu problem, saying people should prepare for the possibility that schools will be closed. Obama confirmed that an infant has died of the disease in the United States and urged state and local authorities to report suspected cases immediately to federal authorities.