CNN) -- In the biggest upset of the year, the No. 2 Republican in the House, Eric Cantor, has lost to his tea party opponent in his primary in Virginia, CNN projects. With 75 percent of precincts reporting, Cantor trailed his opponent Dave Brat 56% to 44%.
"This came out of nowhere," said Mark Preston, CNN's executive political editor, who said a defeat for Cantor would have national implications since he has been viewed as a potential speaker.
Brat is an economics professor at Randolph-Macon College outside Richmond.
Most Republicans view Cantor, 51, as the most conservative member in the House leadership lineup. He was President Barack Obama's chief foil in budget negotiations in 2011, a role he proudly points out during this campaign season.
In a phone interview with CNN on Monday, Brat argued that Cantor is more attentive to donors in New York and California and big business groups than he is to enacting an agenda based on Republican ideals.
"While he's got an eye on the speaker job, he's turned his back on his constituents," Brat said.
He noted that Cantor and other GOP leaders have dropped their free market principles and not done enough to address looming deficit problems.
Brat attempted to frame his challenge as another case of a grassroots conservative taking on the GOP establishment, a major theme in Republican contests this year.
Brat has tried to make immigration reform the central issue, and said Cantor's position would hurt the economy.
Brat said Cantor's campaign ads have actually helped elevate his name ID and predicted he would win.
"On Tuesday you're going to have a shock on your hands," he predicted.