WASHINGTON – Pennsylvania Democratic Sen. Arlen Specter lamented an increasingly bitter partisan atmosphere in the U.S. Senate and urged his colleagues to bring back civility Tuesday during his valedictory floor statement.

After 30 years, the longest tenure for a senator in state history, Specter is moving on, defeated in his bid for a sixth term after switching from the Republican Party to the Democrats in an effort to survive one more time.

"Politics is no longer the art of the possible when senators are intransigent in their positions," Specter said during the address. He deplored how some conservative Republican senators supported Tea Party insurgents that knocked off incumbents in the GOP primaries, calling it "a form of sophisticated cannibalism."

There's no way senators can trust each other with that kind of warfare, Specter said. He said that "abuses" of Senate rules had limited the ability of individual senators to offer amendments and allowed the mere intent to filibuster to block the chamber's agenda.

About a third of the Senate stayed in the chamber to hear Specter's speech, including several Republicans, and afterward they crowded around to congratulate him. "Great speech," Sen. Diane Feinstein (D., Calif) said, giving Specter a hug and a peck on the cheek.

Sen. Bob Casey (D.,Pa.) rose to praise his colleague, saying that Specter belongs on the list of notable Pennsylvania figures with such names as William Penn and Benjamin Franklin. "His impact will be felt for generations, not just decades but generations," Casey said.

Senate Majority Whip Richard Durbin (D.,Ill.) said that as long as he's around he will carry the banner to get cameras in the Supreme Court, a longstanding Specter proposal that he lobbied for once again during the floor statement.

Specter, 80, is working on a memoir about the experience of his party switch (his third book), and is expected to practice law and teach a course in the Supreme Court at Penn Law School. He also wants to provide commentary on the big issues of the day for public radio or a TV or cable network, and is available if the president needs him for anything.

In addition to his talent for political comebacks, Specter has survived two bouts with Hodgkin's disease, a brain tumor and cardiac arrest following heart-bypass surgery.

"It was very gratifying . . . there were a lot of people there," Specter said in a brief interview afterward. He explained the contradiction between spending much of his speech diagnosing the ills of the Senate and closing his speech with optimism that it will get better.

"I didn't say this in the speech . . . but the Senate is a lot smarter than I am," Specter said in the interview.

He added that some conservative Republicans, have said, in effect, "good riddance" to Specter's involuntary retirement from the Senate. They call him self-serving, and blame his view of the importance of compromise for driving up government spending and debt.

But this wasn't a day to air those kinds of criticisms. Instead it was a rare pause when senators gathered to witness a historic moment and show respect to a departing colleague.

Contact staff writer Thomas Fitzgerald at 215-854-2718 or tfitzgerald@phillynews.com