Casey vowed neutrality but now backs Obama

After vowing not to endorse a Democratic candidate for president until his state's primary next month, Pennsylvania Sen. Bob Casey changed his mind.

The Democrat threw his support behind Sen. Barack Obama Friday, insisting that he could no longer stay on the sidelines.

In a news conference after his public announcement, the senator spoke of his decision to make a potentially game-changing endorsement.

"For a long, long time I was not only neutral but an undecided voter," said Casey.  "That changed recently."

"I believe in this guy like I've never believed in a candidate in my life, except my father," Casey continued, comparing Obama to two term Pennsylvania Gov. Robert Casey, Sr.

Casey made his endorsement earlier at the University of Pittsburgh, standing shoulder to shoulder with his presidential pick.

Video Casey’s remarks March 28: See Sen. Bob Casey’s remarks while endorsing Barack Obama in Pittsburgh, Pa. NBC News Web Extra

A source close to Casey said the senator's "enough is enough" attitude regarding the recent party infighting between Obama and Sen. Hillary Clinton lead to his change of heart.

On Friday, Casey said that he's been impressed by Obama's "character in this campaign... He's appealed to 'the better angels of our nature,' to use [Abraham] Lincoln's line, under very difficult circumstances in a presidential campaign like this."

"I really believe that in a time of danger around the world and in division here at home, Barack Obama can lead us, he can heal us, he can help rebuild America," he added.

Terry Madonna, the Director of the Center for Politics and Public Affairs at Franklin and Marshall College, went even further. He said that Casey thought "what was going on was ruinous and destructive."

For more than 30 years, Madonna has covered Keystone State politics and spoke with Casey in recent weeks while the senator remained uncommitted.  "Primarily, this is the best way to move the [nomination] process forward and not the let the bitterness continue within the party," said Madonna.

While the timing of the announcement was unexpected, the choice of Obama over Clinton may not shock those who remember the 1992 Democratic convention.

At the time, Casey's father was the state's pro-life governor, a position held by a small minority of elected Democrats. That stance is widely believed to be the rationale that led then-nominee Bill Clinton to deny the elder Casey a speaking role during the convention.

"Dad was beyond incensed," over the events at that convention, Madonna said, but he suspects it's not the singular motive for the endorsement.

He said the Caseys' "dance to their own tune," again referencing their positions as pro-life Democrats in a pro-choice party.  But Madonna said the 1992 convention is the "backdrop" for which Casey endorsement must be viewed.  "It's my hunch that [the 1992 convention] prevented him from having a close relationship with the Clintons."

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