It's not often someone drops a bombshell on the U.S. Senate, but that's what happened as Sen. Arlen Specter switched parties.

Senators in both parties seemed stunned by the news, as many had thought Specter would simply remain in the GOP, where he has fought with his own party over the years.

In a news conference, Specter told reporters that he had watched his party move more and more to the right, leaving him little option but to choose a different path.

"I know that I'm disappointing many of my friends and colleagues," Specter said.

Earlier, Specter went into the regular Republican lunch for the last time, telling his colleagues of his decision.

He emerged smiling about ten minutes later, no limbs broken, no food on his jacket.

"The disappointment runs in both directions," Specter said.

While Specter has gotten a lot of barbs from Republicans, the move disappointed some more conservative Republicans, worried that their party is increasingly becoming one that only has significant roots in the South.