Veteran Pennsylvania Sen. Arlen Specter switched from the Republican to the Democratic Party on Tuesday, saying he has found himself increasingly "at odds with the Republican philosophy."
"This is a painful decision. I know I'm disappointing many of my colleagues," he said at a news conference announcing the move. "The disappointment runs in both directions.
"I'm putting principle at the top of the list," he added. Read full article »
CNN's Ed Hornick and Deirdre Walsh contributed to this report.