Cantor's defeat is perhaps one of the biggest upsets of any congressional race in the past few years and a welcome win for tea partiers who had wanted to defeat as many establishment Republican candidates as possible.
In his loss, Cantor became the first House majority leader in the history of the United States to be defeated in a primary while also holding that position. The loss also makes it appear that the next Congress will be without a Jewish Republican, according to The Jewish Week.
"Cantor is the first to lose a renomination bid as a sitting House Majority Leader after 55 successful attempts since the creation of the office in 1899," University of Minnesota political science professor Eric Ostermeier said in an email to TPM on Tuesday.
Arguably, the closest analogy was House Speaker Tom Foley, who lost a re-election fight in 1994. Before that the last sitting speaker to be defeated was Galusha A. Grow in 1862.
Cantor's challenger had not received significant support from big-spending outside tea party groups like Matt Bevin's bid against Senate Minority Leader Mitch McConnell's (R-KY). Instead, Brat is a little known economics professor at Randolph-Macon College in Virginia who ran a single-issue campaign against Cantor on immigration.
The loss was shocking to everyone, including Cantor, who delivered brief but solemn remarks at his election night party.
"Obviously we came up short," Cantor said.
Days earlier, Cantor's campaign hinted that Brat may not just be a fly that could easily be flicked away but simultaneously expressed confidence that the majority leader would win re-election.
"We have always taken every race seriously, and we're taking this one seriously," Cantor told The Hill. "We're feeling really good about where we are and looking for a big win Tuesday."
Cantor's campaign also sent out mailers arguing that he's largely responsible for blocking immigration reform, signs, perhaps, that Brat seemed like more of a threat than he appeared publicly.
Tea Partiers were visibly giddy about Cantor's loss.
"It doesn’t matter what office you hold or how powerful you are. If you lose touch with activists on the ground, then your seat is in danger," FreedomWorks president Matt Kibbe said in a statement.
Mississippi State Sen. Chris McDaniel (R), a tea party favorite who is in a tight runoff election against Sen. Thad Cochran (R-MS) also sent out an email titled "we just beat Eric Cantor."
This post was updated.