In his victory speech at the Valley Forge Military Academy and College, an exuberant Sestak, with wife Susan and daughter Alex at his side, said the people had made their voices heard in a call for an end to politics as usual.
"This is what democracy looks like: a win for the people over the establishment, over the status quo, even over Washington, D.C.," Sestak said.
Graciously, he called Specter, a cancer survivor, "someone who is truly courageous," drawing a round of applause from the crowd. "He has devoted his entire life to public service," he said, "and he and his lovely wife, Joan, deserve our thanks for that."
Sestak promised that his victory meant Pennsylvania would see a Senate campaign between "two very different philosophies" and drew a round of boos when he mentioned former President George W. Bush, whom he had labored to connect with Specter on the campaign trail.
Sestak will face Republican Pat Toomey, a former congressman from Allentown with strong backing from both the GOP establishment and conservative tea party activists. Toomey handily defeated conservative activist Peg Luksik.
In his remarks, Specter pledged to support Sestak. "It is vital that we keep this seat in the Democratic Party's hands," he said.
Sestak's victory was sweeping. He carried every county but Philadelphia, Dauphin, and Lackawanna. And although Specter won Philadelphia handily, turnout on a dismal rainy day was not high enough to save him.
With 99 percent of the state's precincts reporting, Sestak received about 54 percent of the vote to 46 percent for Specter, according to unofficial returns.
Specter is the third veteran member of Congress to go down in less than two weeks. Sen. Robert Bennett (R., Utah) and Rep. Alan Mollohan (D., W. Va.) were denied their parties' nominations.