Pennsylvania Sen. Bob Casey plans to endorse Sen. Barack Obama for president today in Pittsburgh, sending a message both to the state's primary voters and to undecided superdelegates who might decide the close race for the Democratic presidential nomination.
Dan Pfeiffer, deputy communications director for the Obama campaign, confirmed that Casey would announce his support during a rally at the Soldiers and Sailors Military Museum and Memorial and that he would then set out with the Illinois senator on part of a six-day bus trip across the state.

The endorsement comes as something of a surprise. Casey, a deliberative and cautious politician, had been adamant about remaining neutral until after the April 22 primary. He had said he wanted to help unify the party after the intensifying fight between Obama and Sen. Hillary Rodham Clinton.

"There are few stronger advocates for working families in Pennsylvania than Sen. Casey," Pfeiffer said.

By coming out for Obama, Casey puts himself at odds with many top state Democrats - including Gov. Rendell, Rep. John P. Murtha and Mayor Nutter - who are campaigning for Clinton.

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