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.
In another gauge of anti-establishment sentiment, Democratic Sen. Blanche Lincoln of Arkansas led in her bid for nomination to a third term but failed to reach the 50 percent threshold needed to avoid a costly runoff.
In another race with national significance, Democrat Max Critz won a special House election to fill out the term of the late Democratic Rep. John Murtha in southwestern Pennsylvania. Both political parties spent roughly $1 million to sway the outcome, and highlighted the contest as a possible 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 the seat Murtha long made his own.
With 79 percent of precincts reporting, 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.
President Barack Obama had endorsed Specter, who also had the support of Gov. Edward Rendell, the Democratic state and county parties, and the AFL-CIO.
Sestak made Specter's switch the central issue of his challenge, saying he was a political opportunist who could not be trusted. He said people were fed up with politics as usual and it was time for a "new generation" of leadership.
Sestak, 58, would not sit down when party leaders asked him to defer to the veteran Specter. Sestak, serving a second term in the U.S. House, is a retired admiral who served for 31 years in the Navy, including a stint on the Clinton White House staff and command of a carrier battle group off Afghanistan in 2001.
Obama was omnipresent for Specter in television and radio advertisements, telephone robo-calls, literature, and election-day "door hangers."
But when the polls tightened, Obama and Vice President Joe Biden stayed away from Pennsylvania, despite pleas from state Democrats and the Specter campaign. White House aides said they wanted to avoid risking the president's political capital in another losing effort.
Indeed, on Tuesday, Obama visited Youngstown, Ohio, 22 miles from the Pennsylvania line, to talk about the economy. Obama has had a miserable track record of personal campaigning for Democrats. Gubernatorial candidates for whom he campaigned lost in New Jersey and Virginia last fall, and a last-minute visit to Boston could not help Democrat Martha Coakley hold the late Sen. Edward M. Kennedy's seat for the party in a January special election.
A cold rain fell across Pennsylvania on Tuesday, testing Specter's voter-turnout operation, which was staffed by union supporters and party organizations.
Sestak, who polls suggested had more fired-up backers, relied on volunteers but spent the bulk of his cash, a little more than $4 million, on TV and radio.
Specter is barred by state law from running as an independent. Unlike Connecticut, where Sen. Joe Lieberman won re-election after losing the Democratic nomination in 2006, Pennsylvania prohibits candidates who run in a partisan primary from getting on the ballot as independents.
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.
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.
High unemployment, an economy just now emerging from the worst recession in generations and Congress's decision to bail out Wall Street giants in 2008 all added to voters' unease, polls said. In a survey released shortly before the polls closed, ABC said voter expectations for the economy had turned optimistic for the first time in six years. At that, only 33 percent of those polled said so in the network's polling, compared with 29 percent saying the opposite.
In Arkansas, Sen. Lincoln's vote hovered close to the 50 percent needed to avoid a runoff.
Lt. Gov. Bill Halter was running second.
In Oregon, Democratic Sen. Ron Wyden faced little opposition for nomination to a third full term.
So far, one Democrat has lost his race for a new term this year. In West Virginia, Democratic Rep. Alan Mollohan fell in a primary to an opponent who highlighted ethics issues.
The far-flung races took place a little less than five months before midterm elections in which Republicans will challenge Democrats for control of both houses of Congress. Obama backed incumbents in his party's races, but despite the stakes for his legislative agenda the White House insisted he was not following the results very closely.