By Dan Balz and Chris Cillizza
Washington Post Staff Writer
Wednesday, May 19, 2010; A01

Pennsylvania Sen. Arlen Specter (D), a Senate fixture who switched parties a year ago, lost his bid for reelection Tuesday, while in Kentucky, ophthalmologist Rand Paul rode the anti-Washington energy of the "tea party" movement to an easy victory.

On a busy primary election night that put the political establishments of both parties on the defensive, Specter fell to two-term Rep. Joe Sestak. Elected five times to the Senate as a Republican, Specter had the support of President Obama and the political leadership of his state, but he ran into rank-and-file resistance inside his new party and became the third member of Congress to lose his own party's support in the past two weeks.

In the Republican Senate primary in Kentucky, Paul, a political novice and a son of Rep. Ron Paul (R-Tex.), stormed past Secretary of State Trey Grayson, who had the support of Senate Minority Leader Mitch McConnell (Ky.) and much of the Bluegrass State's political establishment. With almost all of the vote counted, Paul had 59 percent, a sign of the power of his and the tea party's small-government message within the GOP.

Although poles apart ideologically, Sestak and Paul both struck anti-Washington themes in their victory statements Tuesday night.

"This is what democracy looks like," Sestak said to a crowd of cheering supporters. "A win for the people, over the establishment, over the status quo, even over Washington, D.C."

"I have a message, a message from the tea party, a message that is loud and clear and does not mince words," Paul said at his victory rally. "We've come to take our government back."

Elsewhere, Democrats held the seat of the late congressman John P. Murtha (D) in a special House election with clear implications for the November midterms. Republicans had hoped to pick off the culturally conservative district to demonstrate their momentum this year. But Democrat Mark Critz, a former aide to Murtha, defeated Republican businessman Tim Burns with relative ease.

In Arkansas, Democratic Sen. Blanche Lincoln, another embattled incumbent who had Obama's support, fell short in her bid to win renomination outright and now faces Lt. Gov. Bill Halter in a potentially perilous June 8 runoff.

Tuesday's results were the most powerful indicator to date of the voter anger and dissatisfaction that has shaped the political climate all year.

Democrats remain on the defensive heading toward November, in large part because of divisions over Obama's agenda, the high jobless rate and the size of the federal budget deficit. The Kentucky race underscored the energy of anti-government conservatives who intend to shake up the capital. But the results in Pennsylvania's special House election will raise questions about whether Republicans will be able to take control of the House in November, as many of their leaders have predicted.

The Senate primary in Pennsylvania drew more attention than any other race Tuesday because of Specter's longevity in office and his surprise decision to switch to the Democrats last year.

The senator provided the party with a critical vote needed to break GOP filibusters against health-care legislation. In return, Obama strongly endorsed him in the primary, as did Pennsylvania's Democratic establishment, led by Gov. Edward G. Rendell and Philadelphia Mayor Michael Nutter.

Sestak, a Navy veteran, refused to follow the script. He mounted a long-shot challenge, highlighting his military service and casting himself as an outsider against the insider Specter. His campaign gained altitude after he aired a devastating ad that cast the incumbent as an ally of former president George W. Bush and as a politician motivated more by self-interest than the public interest. The ad quoted Specter as saying his party switch "will enable me to be reelected."

Sestak will face Republican Patrick Toomey, who won nomination easily, in a November race that will present a clear contrast for voters and is likely to be closely fought.

Paul's victory in Kentucky marked the second time in two weeks that tea party activists flexed their muscles in the Republican Party. On May 8, Sen. Robert F. Bennett (Utah) was defeated in his bid for renomination at a party convention after being targeted by tea party supporters because of his vote to bail out big banks and financial firms.

Paul started as a long-shot candidate, but he successfully tapped the fundraising network of his father, who ran for the Republican presidential nomination in 2008 as a libertarian conservative and attracted a passionate following but won no primaries. By Tuesday, Paul was the clear favorite.

In Kentucky's Democratic Senate primary, Attorney General Jack Conway defeated Lt. Gov. Dan Mongiardo in a close contest.

The House election in western Pennsylvania ultimately may hold the most meaning for November, when the Democratic majority will be at risk. The district was the only one in the nation that supported Democrat John F. Kerry for president in 2004 and then backed Republican John McCain in 2008.

Voters there elected Murtha to 18 terms, and he was legendary for returning federal money to this economically hard-pressed region. Republican Burns sought to nationalize the contest, campaigning against Washington and the Democratic agenda. But Democrat Critz said he too opposed the new health-care law and presented himself as a foe of abortion and a backer of gun rights.

In Arkansas, the Democratic primary battle between Lincoln and Halter was in many ways a proxy war between organized labor and the White House. Obama endorsed Lincoln and appeared in ads for her. But unions spent millions on television and radio ads -- not to mention an extensive field program -- to oust the incumbent, whom they believe has been insufficiently loyal on issues such as health care and the Employee Free Choice Act.

On the Republican side in the state, Rep. John Boozman avoided a runoff in a crowded GOP field.

In Oregon, the fourth state with primary contests on Tuesday, former governor John Kitzhaber (D) won nomination for a comeback attempt, while former professional basketball player and political novice Chris Dudley was leading in the Republican gubernatorial primary.