U.S. House Majority Leader Eric Cantor lost to David Brat in a primary election Tuesday.

Eric Cantor delivers a concession speech Tuesday. (AP Photo/Steve Helber)

How to explain a loss this seismic? Especially when the incumbent spent about as much at steakhouses as his opponent spent on his whole campaign (that "factoid will define this race," Dave Weigel wrote on Twitter).

  • New York Times explainer site The Upshot takes an unusually honest tack in the headline for its explainer: "Why Did Cantor Lose? Not Easy to Explain." Nate Cohn tries anyway:

    Tea Party candidates have generally struggled this year, and Mr. Cantor outspent his underfunded opponent by a huge margin. Mr. Cantor easily defeated a primary challenge in 2012, generally a better year for the Tea Party, by nearly a 60-point margin. Turnout was not unusually low: More than 63,000 votes have been counted so far, up from around 47,037 in 2012.

  • FiveThirtyEight's Harry Enten looks for meaning in a "less commonly discussed" dimension of DW-Nominate scores, which rank members by votes. While Cantor is "more conservative than any of the Republicans thought to be in trouble in 2014," the second dimension "has come to represent something like an insider vs. outsider (or establishment vs. tea party) spectrum," Enten writes.

    I don’t want to claim that Cantor’s defeat was all that predictable — it wasn’t. But he does share something in common with those who lost before him, as DW-Nominate places him firmly on the establishment side of the spectrum.

  • Vox's Ezra Klein offers "provisional thoughts" rather than an overarching explanation (Vox does have a "primer" on Brat). The Republican Party, he writes, "has a serious data problem."

    In 2012, Mitt Romney's internal polls were garbage. This year, Eric Cantor's internal polls showed him up by more than 30 points. Something is deeply wrong with the GOP's campaign infrastructure if the party's presidential nominee and the party's House majority leader can't rely on their pollsters.

Thanks for the explanations, but why didn't anyone see this coming? "Like most congressional primaries, we didn’t know much about this race," Danny Vinik writes. "Independent pollsters generally stay away from these races. District-level polling is just very hard to do accurately. In other words, data can only tell you so much."

Dave Weigel (him again!) noted that The Washington Post wasn't expecting Brat to win:

On Twitter, Post reporter Robert Costa directs readers to this May 14 story, which said Brat was a "potential threat to Cantor’s hold on his solidly Republican, suburban Richmond district."

Finally: