Updated: 11:10 p.m.

PHILADELPHIA — Sen. Arlen Specter was ousted Tuesday by Pennsylvania voters in the Democratic primary, an abrupt end to the storied, 45-year political career of the former Republican that sets up a competitive general election between Rep. Joe Sestak (D) and former Rep. Pat Toomey (R).

The anti-incumbent mood that swept a sitting Senator and incumbent Congressman from office earlier this month in Utah and West Virginia landed in the Keystone State and propelled Sestak to a come-from-behind victory over Specter, who had the backing of the Democratic establishment at home and in Washington, D.C.

“It’s been a great privilege to serve the people of Pennsylvania, and it’s been a great privilege to be in the United States Senate. I’ll be working very hard for the people of the commonwealth in the coming months,” Specter told supporters during brief remarks Tuesday night.

The Associated Press called the race for Sestak a little after 10 p.m., and he was maintaining a 53 percent to 47 percent lead over Specter at press time.

Sestak carried Allegheny County and other counties in the Pittsburgh region, which proved to be key to his victory.

Inside the ballroom at the Sheraton Philadelphia City Center Hotel, Specter’s supporters were subdued as news of his defeat spread.

Toomey, who narrowly lost a GOP primary challenge to Specter in 2004, easily won his party’s Senate nod Tuesday over minimal opposition.

Earlier Tuesday, both the Specter and Sestak camps were cautiously optimistic that a win was within their grasp. Each candidate began the day by voting before a throng of reporters covering the closely watched race — Specter in his upscale East Falls neighborhood in Philadelphia and Sestak in the suburban Philadelphia 7th district where he first won in the Democratic wave of 2006.

Specter and Sestak both focused on turning out the Democratic vote in greater Philadelphia, crisscrossing the region Tuesday for appearances at polling places and stops popular with their party’s faithful on election days. For Specter, that meant a swing through the Famous Fourth Street Delicatessen in the Queens Village area of south Philly.

Specter was greeted outside by a collection of labor union supporters, while inside, prominent city and state Democratic politicians lunched on traditional Jewish deli fare. The former Republican shook hands and was greeted as though he’d been a Democrat all his life, with a brief chant of “Arlen, Arlen, Arlen” breaking out among those in attendance.

Pennsylvania Gov. Ed Rendell (D), who arrived at the restaurant as Specter was leaving, conceded that the poor weather could depress overall voter turnout and diminish the Senator’s prospects. But the governor, a strong Specter supporter, pushed back on the notion that his party switch a little more than a year ago should be a reason for Democrats to reject him in favor of Sestak.

“I think generally a larger turnout would have benefited Arlen,” Rendell told reporters midday Tuesday, adding: “It’s always difficult to switch parties. But I’ve been reminding people that Arlen Specter didn’t switch parties on his own. The vice president of the United States, the president of the United States, the governor of Pennsylvania, the mayor of Philadelphia, all of whom were pretty good Democrats — we asked him to switch; we asked him to switch.”

Ninety minutes before the polls closed, Specter appeared optimistic and relaxed. He ventured into the election night ballroom to greet the media and voluntarily took questions from reporters until they were finished and began to peel off one by one. He interspersed serious answers with jokes about the course of the campaign, but he was clear on one thing: He expected to win and predicted a Sestak candidacy would doom Democrats in the general election.

“If Sestak is nominated, he’s not going to beat Pat Toomey. He really isn’t,” Specter said.

Sestak pointedly disagreed, arguing repeatedly Tuesday that Specter’s incumbency and decades of Washington service would give Toomey the upper hand in November. Sestak, who is not immune to the perils of incumbency after two terms in the House, moved to position himself as the political outsider running against insider Washington.

At a late-morning appearance at a polling station in the West Mount Airy neighborhood of northwest Philadelphia, just minutes from Specter’s home in East Falls, Sestak said that he respected the Senator’s service but it was time for a new generation of leadership. Sestak said his “gut feeling” was that he would beat Specter, and he attempted to cast his predicted victory as a win for “the people.”

But in a reflection of his challenger status and the dogfight the two Democrats found themselves in down the stretch, Sestak hit Specter and hit him hard over the party switch, subtly but unmistakably calling into question the Senator’s character.

“The reason we have to win is that Arlen Specter will lose against Pat Toomey,” Sestak told reporters outside the Summit Presbyterian Church. “He comes from a political background, where people in Washington, D.C., often say things but then they switch parties or change their words.

“For me it’s not about incumbency,” Sestak added. “I found that Washington, when I went down there, is composed of too many politicians who change their parties or change their position to keep their job.”

At the very least, Sestak’s pitch worked on 57-year-old educator and Democratic activist David Meketon. He ultimately voted for Sestak after much soul-searching.

“It was impossible. I changed my mind five or six times,” Meketon said. “Sestak —his character and his values better reflect my values than do Arlen’s.”

However, Specter supporters remained confident that the incumbent Senator’s superior turnout machine would carry the day. Union officials and party activists said Specter’s operation was far better at the campaign level and because of the ground game provided to his re-election effort by organized labor.

Pat Gillespie, business manager for the Philadelphia Building Trades Council, noted that his organization supported Specter when he was a Republican. He argued that Specter’s party switch was more a national issue than a local one, while contending that Sestak’s support in the key Democratic region of southeast Pennsylvania was too thin for him to be successful.

“Arlen Specter would win the southeastern region by maybe three or four to one, in some elections. So it’s nothing unusual for people to vote — who are Democratic registered people — to vote for Arlen Specter. There’s nothing new there,” Gillespie said in an interview. “The important part about this election, and Congressman what’s his name? Sestak. I asked what his name is because he doesn’t have much of an identity here.”