Arlen Specter Press Conference

President Barack Obama and Vice-President Joe Biden welcome Sen. Arlen Specter to the Democratic caucus.

Update: Sen. Barbara Mikulski is not happy Harry Reid will let Specter retain his senioity. Obama and Biden will support Specter in the Democratic primary.

"I won't be happy if I don't get to chair something because of Arlen Specter," said Sen. Barbara Mikulski (D-Md.), who sits on the Appropriations Committee with Specter and is fifth in seniority among Democrats behind Chairman Daniel Inouye (Hawaii), Sens. Robert Byrd (W.Va.), Patrick Leahy (Vt.) and Tom Harkin (Iowa). "I'm happy with the Democratic order but I don't want to be displaced because of Arlen Specter," she said.

One senior Democratic lawmaker told The Hill that the Democratic Conference will vote against giving the longtime Pennsylvania Republican seniority over lawmakers like Harkin, Mikulski and Sen. Dianne Feinstein (D-Calif.) when they hold their organizational meeting after the 2010 election.