In a historic and surprising upset, Republican House Majority Leader Eric Cantor of Virginia lost his seat Tuesday in a primary against little-known and underfunded Tea Party challenger David Brat. Cantor spent $5 million on a House seat he thought was endowed. In a quintessentially American underdog story, Brat, an economics and ethics professor at Randolph-Macon College in Ashland, came from nowhere, spent $122,000, had virtually no national support – and won in a high-turnout, 56-44 landslide. In other words, reports of the true grassroots Tea Party’s demise are greatly exaggerated.

In South Carolina, Republican Sen. Lindsey Graham handily won his primary against a divided field. Even before primary day, he crowed that beating the Tea Party is “[m]ore fun than any time I’ve been in politics.” He added, “People are really saying, ‘OK, enough already.’ They’re starting to push back from trying to define conservatism in a fashion where there is no room for solving problems.” Evidently the people of Virginia disagreed with that assessment and decided it was time for solving a problem.

Cantor’s loss is a critical warning to the GOP establishment and leadership, particularly on immigration, which was a key issue in the campaign. With Cantor’s defeat, the prevailing wisdom is that “comprehensive” reform is now dead for the year.

Then again, conventional wisdom was also that the Tea Party was dead.

Immigration reform is a hot topic, and Cantor and the GOP leadership seem a bit too eager to team up with Democrats for some form of path to citizenship for illegal aliens. Though Cantor boasted in campaign mailers of blocking a Senate effort “to give illegal aliens amnesty,” National Journal reports, “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.” Voters took notice of his inconsistent messaging, and his loss is a rebuke to Republicans who don’t stick to a measured, step-by-step approach. We’ll see if they heed the message.

It’s important to note that Brat also won on his unflinching opposition to ObamaCare. That’s not as sexy a play as immigration, but it was a major campaign theme for him.

Cantor was seen as next in line to become speaker. Now that he’s not returning to Congress, however, it will spark a competitive battle to replace him in the GOP leadership. Majority Whip Kevin McCarthy of California, the third-ranking Republican, isn’t exactly a Tea Party darling, perhaps opening the field a bit.

Though by all appearances Cantor lost on immigration, he really lost on the assumption that he could not lose. It’s the establishment versus grassroots mindset. The message from voters, however, was clear: Elected representatives should not take for granted those who elect them. Or send them home.

Brat appears to be a capable, articulate candidate, well versed in the free market and public policy. As he put it after his victory, “[T]he problem with the Republican principles is that nobody follows them.” And if Cantor does not now immediately throw his support behind Brat – and those underlying principles – then he really is part of the problem, not the solution.