PERHAPS it was a freak storm. On June 10th Eric Cantor, the second most powerful Republican in the House of Representatives, lost a primary to a Tea-Party challenger. Such defeats are rare. In no year since 1970 have more than ten incumbents lost primaries, unless electoral districts have just been redrawn. Though the GOP often appears more fractious than the president’s party, Democrats have had more candidates taken out in primaries than Republicans over the past few decades, according to Bloomberg News. Nor is Mr Cantor’s fate typical of this cycle. Brookings, a think-tank, reckons that thus far in 2014, 81 Tea-Party candidates have lost primaries while only 16 have won.

That the Republicans looked set to replace Mr Cantor as Majority Leader with Kevin McCarthy (pictured), a congenial Californian with an MBA, adds to the impression that congressional business will continue as usual. Mr McCarthy is from the same ideological pole as Mr Cantor and is known to be a good fundraiser. His political action committee has made small donations to 84 of his colleagues in this election cycle. He is less impressive in front of a microphone, however. Sometimes he attacks the English language more energetically than he attacks Democrats.

Yet it is precisely the unlikeliness of Mr Cantor’s loss that makes it alarming for Republicans in the House. Most GOP members have more to fear from their primary voters than from the general election in November. The Cook Political Report and RealClearPolitics, two political augurs, agree that there are only 17 competitive House races out of 435, so for most Republican congressmen the risk of suffering the same fate as Mr Cantor feels like the bigger threat to their jobs. Nor do Tea-Party challengers have to win many races to be influential. Only a couple of victories are required to get House Republicans worrying about who might be next, and calibrating their votes to make sure it is not them.

This helps to explain why there are so many theories about why Mr Cantor lost. Some say it was his line on immigration reform—he once suggested that migrants who arrived in America as small children should be treated kindly—and conclude that immigration reform is now dead in the House. Others think it was his friendliness to banks, and will be careful to distance themselves. “The crooks up on Wall Street in some of the big banks,” Dave Brat, the college professor who defeated Mr Cantor, told one radio host, “I’m pro-business, so I’m just talking about the crooks — they didn’t go to jail, they’re in Eric’s Rolodex.” Those who think Mr Cantor spent too much time building a national profile will eat even more barbecue at church picnics. Because nobody knows what finished Mr Cantor, the best defence is to assume it was all of the above and vote accordingly.

The immediate tests for Republicans will come in a handful of votes on business-friendly measures. Hostility to government support for big business on the right of the Republican Party is currently focused on the Export-Import Bank, an agency of the government that provides trade finance. The bank is due for reauthorisation in September. It may not get it.

Another test will be the renewal of the Terrorism Risk Insurance Act, under which the federal government helps to underwrite catastrophic losses from terrorist attacks, due by the end of the year. Mr Cantor’s scheme to top up the Highway Trust Fund by ending Saturday deliveries by the postal service is unlikely to move.

Defeat on any of these points would make some businesses question whether the Republican Party is the best vehicle for the sort of policies that they see as good for growth. Already it can be hard to spot the difference between what some left-wing Democrats and some right-wing Republicans say about banks. Moreover, though the party seemed to have absorbed the lesson last year that shutting down the government and flirting with a sovereign default is bad for America’s credit rating, that escapade has not inflicted much long-term damage on Republicans in opinion polls. Mr Cantor’s loss makes a repeat performance marginally more likely.