Imagine those Amtrak conversations between Joe Biden and Arlen Specter.

The vice president’s devotion to taking the train home to Wilmington, Del., is legend. It turns out that besides reinforcing his commitment to mass transit, Biden’s commute also gave him hours and hours of uninterrupted quality time with the senator from Pennsylvania.

Which he used to urge Specter to ditch the Republicans.

“We have talked over every problem under the sun and under the moon,” said Specter, at a welcome-to-the-Democratic-Party press conference with Biden and President Obama.

Biden, Washington’s most compulsive talker, and Specter, one of the Senate’s most self-absorbed egos, rode the rails, sharing their every thought. Probably not in the quiet car. You’d think that by the time one of them paused to take a breath they’d be in Montreal.

On Wednesday, Biden was bounding around with excitement at his coup, and who could blame him? Heaven knows Obama deserved some good fortune. Other than Specter’s defection, the best news the president got on his 100th day in office was probably word that the Department of Homeland Security had eliminated the threat of swine flu by changing its name to the H1N1 flu.