The end of the line for Snarlin' Arlen

Entering his fourth decade in the Senate, Democrat-turned-Republican-turned-Democrat-again Arlen Specter was finally ousted last night by liberal primary challenger Joe Sestak.

At one time -- in the not-so-distant past -- Specter was an increasingly rare breed of politician: A legitimate centrist and principled, independent thinker who gave leadership fits and drew the wrath of the bases of both parties. He was one of the first Republicans to publicly criticize President Bush, drawing the ire of conservatives everywhere. His pseudo-small government mindset and support for the Afghanistan and Iraq wars made him deeply unpopular with the Democratic base, who turned out in droves to support Sestak last night.

Specter switched parties last year because of a primary challenger from the right, former Club for Growth President Pat Toomey -- a true-blue conservative. As Toomey's stock rose, GOP leadership avoided giving Specter much support due to his questionable conservative credentials. This obviously was the sole factor informing Specter's decision to become a Democrat in April 2009. Our thoughts at the time can be found here.

After the dust settles, Arlen Specter will undoubtedly be remembered as a tremendous public servant with a distinguished record of independence. However, in the late stages of his career, he became a lap dog for the Obama administration, folding like a tent and voting with the Democrats on virtually every major item of import in an effort to curry favor with party leadership and generate support from the party's liberal base. In an effort to save his career, he compromised his once-legendary independent principles and became a caricature of what's gone so terribly wrong in Washington.

Chris Matthews said it best last night: A politician who changes parties to get re-elected is like the guy who put on a dress to get a seat in a lifeboat.

The Arlen Specter of 1995 was a true original, and an invaluable part of a Senate that requires compromise and civility.

But Americans have no use for the Arlen Specter of 2010.