(CBS News) - Be afraid, be very afraid. In February, a top GOP aide explained why immigration reform was never going to happen this year. "The Chamber [of Commerce] and downtown [lobbyists] want it, but they're not going to primary anyone." The fear of a backlash from grass-roots conservatives was hard to predict before Majority Leader Eric Cantor lost in a stunning GOP primary defeat, and it has now become more so.
Stunner: Eric Cantor loses re-election bid What does Eric Cantor's loss mean?How did David Brat defeat Eric Cantor?There may be many reasons Cantor, a seven-term incumbent, lost to David Brat, a professor at Randolph-Macon College in Ashland, Va.
Worry among Republicans that he was backing some form of immigration reform that would allow sweeping legalization of the undocumented population was the crystallizing issue.
"I think it's big," said Brat. "It's the most symbolic issue that captures the differences between me and Eric Cantor in this race." Conservative talk show host Laura Ingraham and other conservative pundits are certainly claiming the victory as a blow to the push for legalization.
But suspicion about Cantor's immigration designs might have also morphed with anger that Cantor was trying to have the issue both ways, pretending he was a movement conservative who opposed amnesty and then backing Speaker John Boehner's immigration principles, which those same conservatives saw as a form of amnesty as well as authoring his own version of the DREAM Act, to give legal status to young undocumented immigrants.
On immigration, he was either wrong or perhaps worse, he was acting just like an insider--squishy on principles. Virginia's GOP primary voters wanted someone who was a consistent conservative.
Or maybe it was because Cantor was seen as a backer of Wall Street elites, not middle-class folks. Or maybe people bought Brat's claim that Cantor didn't fight Obama hard enough (the irony being that Obama really dislikes Cantor).
Whatever the reason, the lesson for other Republicans will be clear: If you aren't consistent, doom can come swiftly and unexpectedly.
This election season has offered plenty of races where GOP establishment incumbents have swamped grass-roots, movement challengers. Senate Minority Leader Mitch McConnell in Kentucky, Sen. John Cornyn in Texas, for example. And, on the same night Cantor lost, Sen. Lindsey Graham won in South Carolina with 59 percent of the vote.
Graham is a stronger supporter of immigration reform and a pathway to citizenship for illegal immigrants than Cantor, and he was able to survive. But if you are a nervous Republican member of Congress, the lesson you're going to take is the one that keeps you alive: Don't fall out of favor with your activist base.
If you do get into trouble, even the traditional weaponry might not save you. Cantor outspent his opponent 20-to-1. Cantor had the power to deliver things to his district. Cantor was seen as next in line to replace John Boehner as speaker of the House, which would have meant even more power and prestige for his district.
This is an undiluted version of the lesson being taught in Mississippi where Sen. Thad Cochran's incumbency--and the funnel of federal spending that goes with it--aren't protecting him from a Tea Party challenger. Expensive pollsters aren't going to save you, either. Cantor's told him he was up by 35 points going into the election.
Members of the GOP conference who are newly afraid weren't stuffed with great courage in the first place, but remember where we were before Tuesday night. Speaker John Boehner had beaten back the "hell no caucus" of conservatives after the government shutdown and given rank-and-file Republican House members a little room to breathe.
Boehner slapped back the groups he though of as grass-roots con men who were opposing the post-shutdown budget deal. "They're using our members and they're using the American people for their own goals," he said. "This is ridiculous."
Boehner was talking about the groups that claim to speak for the grass-roots, like the Club for Growth and Heritage Action Fund. With those groups scalded, establishment Republicans hoped that Republican members would not be so nervous and follow the strategy promoted by House leaders.
Former RNC Chairman and former Mississippi Gov. Haley Barbour told me that Boehner's public comments were a turning point, giving more common-sense mainstream Republicans control of the reins of the party. Main Street Partnership's Steve LaTourette--whose organization funds moderate Republicans and clashes with Tea Party groups--said the same thing.
If the House leadership needed a member to take a tough vote, they could convince him that his fears of being targeted were overblown. Members no longer had to worry as much about well-financed groups with communications departments harnessing grass-roots anger and pointing it at them.
The problem is that's not what happened in the Cantor race. Those outside groups didn't play the role in this race that they have in other races that have been labeled as Tea Party vs. Establishment fights. (Though that didn't stop them from pretending they had a hand in Brat's victory.) So the message is the refreshing and reaffirming one that it's the voters who can turn on you. Brat's win will encourage more attempts, and whether the Cantor defeat can be replicated elsewhere doesn't matter. All incumbents will think there is a monster hiding under their bed--and maybe they're right.
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