WASHINGTON -- Democratic Sen. Arlen Specter lost his bid for a sixth term Tuesday night, a party-switching veteran sent down to defeat by voters rejecting experience and clamoring for change. Meanwhile, political novice Rand Paul rode support from tea party activists to a rout in Kentucky's Republican Senate primary.
In another gauge of anti-establishment sentiment, Democratic Sen. Blanche Lincoln of Arkansas led in her bid for nomination to a third term, but was below the 50 percent threshold needed to avoid a runoff.
A fourth race with national implications played out in southwestern Pennsylvania, where Democrat Mark Critz led Republican Tim Burns in a contest to fill out the final few months in the term of the late Rep. John Murtha.
Each party invested nearly $1 million in that contest and said the race to succeed the longtime Democratic lawmaker was a bellwether for the fall.
Taken together, the busiest night so far of the primary season was indisputably unkind to the political establishments of both parties. But any attempt to read into the results a probable trend for the fall campaign was hazardous, particularly as long as Democrats held to the seat Murtha long made his own.
Two-term Rep. Joe Sestak was winning 53 percent of the vote, to 47 percent for Specter, and his victory spelled the end of the political line for the state's most durable politician of the past generation.
Sestak's campaign calling-card was a television commercial that showed former President George W. Bush saying he could count on Specter, then a Republican, and then had Specter saying he switched parties so he could win re-election.
Once unleashed, it coincided with a steady decline in Specter's early lead in the polls.
Former Rep. Pat Toomey won the Republican nomination and will run against Sestak in the fall in what is likely to be one of the marquee races in the battle for control of the Senate.
Paul's victory was certain to add Kentucky to that list.
"I have a message, a message from the tea party, a message that is loud and clear and does not mince words: We have come to take our government back," said Paul, a 47-year-old eye surgeon making his first run for office.
But the same energy that helped Paul to victory presented problems to be handled carefully by the Republicans in the run-up to November, when control of both houses of Congress will be at stake.
Paul has said he might not support his fellow Kentuckian, Senate Minority Leader Mitch McConnell, for a new term as party leader. And no sooner had Tuesday's results been posted than Richard Viguerie, a longtime conservative warrior, suggested that McConnell step aside.
The far-flung races took place a little less than five months before the midterm elections. President Barack Obama backed incumbents in his party's races, but despite the stakes for his legislative agenda, the White House said he was not following the results very closely.
Whatever the fate of the parties, public opinion polls -- and the defeat of two veteran lawmakers in earlier contests -- already had turned the campaign into a year of living dangerously for incumbents.
--In Arkansas, Lincoln's vote hovered close to the 50 percent needed to avoid a run-off. Lt. Gov. Bill Halter was running second.
--In Oregon, Democratic Sen. Ron Wyden faced little opposition for nomination to a third full term.
--In Kentucky, Paul had 59 percent of the vote with returns counted from 85 percent of the precincts, compared to 36 percent for Grayson, who had been recruited to the race by McConnell.
In a Democratic primary that commanded far less national attention, Attorney General Jack Conway defeated Lt. Gov. Daniel Mongiardo and will face Paul in the fall.
Eager to avoid long-term fallout from a bruising primary, GOP leaders in Kentucky set a unity breakfast for Saturday.
The state's Senate seat is one of 10 or more that appear likely to remain competitive until Election Day, and one that Republicans can ill afford to lose if they are to make a serious run at challenging the Democratic majority.
The seat is now held by Sen. Jim Bunning, but McConnell was so concerned about Bunning's ability to win a new term that he muscled the two-term lawmaker to the sidelines and recruited Grayson to run.