The issue of immigration policy drew heightened attention on Fox News and conservative talk radio in the past week after news reports documented a surge of undocumented children arriving at the United States border, overrunning processing centers and the Border Patrol.
In an interview just last Friday, Cantor suggested he could work with President Obama to allow a path to citizenship for some children of illegal immigrants already in the country. In the campaign's final days, Brat criticized Cantor for siding with Obama on the contentious issue.
A secondary factor in Cantor's demise was his disconnect from many Republican constituents in the district. The state's redistricting in 2010 made his suburban Richmond district more conservative, adding new areas that he didn't previously represent. As majority leader, Cantor spent less time wooing voters at town halls in Chesterfield County and more time deal-making with Republican leadership in Washington.
"Eric Cantor and I have been through a lot together," House Speaker John Boehner said in a statement late Tuesday night. "He's a good friend and a great leader, and someone I've come to rely upon on a daily basis as we make the tough choices that come with governing. My thoughts are with him and Diana and their kids tonight."
Cantor didn't take the challenge from Brat seriously enough until it was too late. Between April 1 and May 21, he spent nearly $1 million trying to fend off Brat, but his campaign was still dismissive of the challenge even as recently as Monday when reporters questioned why it was spending so much money.
"We lived the exact same thing two years ago," said Ray Allen, Cantor's campaign manager, in an interview with the National Journal before Tuesday's primary. "From 2000 to 2012, we've run TV ads, done direct mail, yard signs."
Cantor won his primary with 79 percent of the vote last year, though he only won less than 60 percent of the vote in the last two general elections — in a Republican-friendly district.
Cantor's loss is also a major defeat for the faint hopes of passing immigration reform in the House. Brat's focus on Cantor's immigration record forced him to be defensive. Cantor sent mail ads touting his opposition to "amnesty for illegal immigrants" even while advocating for an exception for those brought to the country as children — a caveat Brat criticized.
Cantor also ran negative TV ads calling Brat a "liberal college professor" and criticizing him for serving on an advisory board for Democratic Sen. Tim Kaine when Kaine was governor.
Cantor's loss also likely will leave the House Republican caucus without any Jewish members next year, a fact that is particularly painful for some Republicans. "On a personal level, it's a moment of sadness to lose someone who was special and unique," says former White House Press Secretary Ari Fleischer. "Who was proudly Jewish and a proudly Jewish Republican. Eric's loss will be felt," Fleischer said.