RICHMOND, Va. - In an upset for the ages, Majority Leader Eric Cantor of Virginia, the second-most powerful man in the House, was dethroned Tuesday by a little-known, tea party-backed Republican primary challenger carried to victory on a wave of public anger over calls for looser immigration laws.

"This is a miracle from God that just happened," exulted David Brat, an economics professor, as his victory became clear in the congressional district around Virginia's capital city.

Speaking to downcast supporters, Cantor conceded, "Obviously we came up short" in a bid for renomination to an eighth term.

The victory was by far the biggest of the 2014 campaign season for tea party forces, although last week they forced veteran Mississippi Sen. Thad Cochran into a June 24 runoff, and hope state Sen. Chris McDaniel can prevail then.

Cantor's defeat was the first primary setback for a senior leader in Congress in recent years. Former House Speaker Thomas Foley of Washington and Senate Democratic leader Tom Daschle of South Dakota both lost their seats at the polls in the past two decades, but they fell to Republicans, not to challengers from within their own parties.

The outcome may well mark the end of Cantor's political career, and aides did not respond Tuesday night when asked if the majority leader, 51, would run a write-in campaign in the fall.

But its impact on the fate of immigration legislation in the current Congress seemed clearer still. Conservatives will now be emboldened in their opposition to legislation to create a path to citizenship for immigrants living in the country illegally, and party leaders who are more sympathetic to such legislation will likely be less willing to try.

The majority leader had been tugged by two warring forces in his party and in recent weeks sought to emphasize his opposition to far-reaching immigration legislation as Brat's challenge gained force. Last month, a feisty crowd of Brat supporters booed Cantor in front of his family at a local party convention.

Still, neither he nor other House leaders betrayed any serious concern that his tenure was in danger, and his allies leaked a private poll in recent days that claimed he had a comfortable lead over Brat.

In the end, despite help from establishment groups, Cantor's repudiation was complete in an area that first sent him to Congress in 2000.

With votes counted in 99 percent of the precincts, 64,418 votes were cast, roughly a 37 percent increase over two years ago.

Despite that, Cantor polled fewer votes than he did in 2012 - 28,631 this time, compared with 37,369 then.

It was unclear if Cantor intended to remain in his leadership post for the duration of the year or who might replace him in the new Congress if Republicans hold their majority.

Democrats seized on the upset as evidence that their fight for House control this fall is far from over.

"Eric Cantor has long been the face of House Republicans' extreme policies, debilitating dysfunction and manufactured crises. Tonight is a major victory for the tea party as they yet again pull the Republican Party further to the radical right," said the Democratic leader, Nancy Pelosi of California.