UNLIKE colleagues such as Bob Bennett, a senator from Utah unceremoniously dumped by the Republican Party in 2010, Dick Lugar was not caught off guard. He had known for well over a year that he would face a strong, tea-party backed rival in the primary for the Senate seat he has held for the past 35 years. He planned accordingly, voting more conservatively, amassing a large war-chest and cranking up his get-out-the-vote operation. Nonetheless, yesterday Mr Lugar lost the primary by a whopping 20-point margin, to Richard Mourdock, Indiana's state treasurer and a hero to many tea-partiers. Politicians from both parties had described the race as a test of the tea party's strength. As the candidate himself puts it, “Rumours of the death of the tea party have been exaggerated.” Jackie Bodnar, of Freedom Works, a campaign outfit that supports tea-party groups, says his victory will give impetus to tea-party candidates seeking the Republican nomination for Senate seats in Florida, Texas and Utah, among other races. Moreover, Mr Lugar's defeat, says Theda Skocpol, of Harvard, “will send another shudder through the Republican ranks in Congress”. Those who thought the tea-party movement was wilting after helping to propel Republicans to a thumping victory in the mid-term elections of 2010, Mr Mourdock argues, were simply mistaking evolution for disillusion. Randy Harrison, the founder of the Hancock County tea party, bears this narrative out. At first, he says, “we were just a bunch of people getting together and griping.” Over time, his group began to engage more formally in local politics. They have familiarised themselves with—and objected to—the county government's scheme for local improvements. They have invited Republican and Democratic candidates to speak at their meetings (no Democrats have ever accepted), and endorsed some of them, including Mr Mourdock. Several members are now running for local office. Of the 900-odd tea-party groups Ms Skocpol has been tracking around the country, some 600 remain active—a remarkable proportion, she argues, for a maturing protest movement. Tea-party activists, in her experience, display “unusual doggedness”. Mr Harrison agrees. His members are frustrated by Congress's failure to enact the tea-party agenda, from fierce budget cuts to a repeal of health-care reform. But that failure has only caused them to become more meticulous in their approach to politics, he says. They realise it will take several election cycles to install conservative Republicans in enough offices to bring about the change they seek.

In some respects, Mr Lugar presented an obvious target. He is 80 years old, and has been in the Senate almost as long as the average Indianan has been alive. It emerged during the campaign that he no longer owns a house in the state and stays in hotels when he visits. His local election board declared him ineligible to vote, although he was subsequently able to switch his registration to the family farm, of which he is a part-owner. Worse, Barack Obama once cited Mr Lugar as an example of a Republican with whom he could do business. Mr Lugar was co-chair of Mr Obama's inaugural committee. It was easy for Mr Mourdock to portray him as a creature of Washington, so eager to get along with Democrats that he forgot the “Hoosier values” he was elected to defend.

Yet Mr Lugar's record was not so out of keeping with the new orthodoxy. He has pressed consistently over the years for an amendment to the constitution to require a balanced federal budget. He speaks plainly about the need to rein in federal benefits for the poor and the elderly in order to keep America solvent. He opposed Mr Obama's stimulus, his health-care reforms and his three recent requests to raise the limit Congress imposes on public debt.

In fact, Mr Lugar's main sins in the eyes of tea-party activists do not involve fiscal matters at all. They cite his votes in favour of both of Mr Obama's nominees for the supreme court, his support for the DREAM act, which would offer citizenship to certain illegal immigrants brought to the country as children, his willingness to subject America to strict disarmament regimes, and his general inclination to compromise. Mr Mourdock, by contrast, is much more doctrinaire. He argues that the habit of Republicans such as Mr Lugar of striking deals with Democrats is what got the country into its current fiscal straits. He wants to abolish four federal departments: Commerce, Education, Energy and Housing and Urban Development. Whereas Mr Lugar supported Mr Obama's largely successful bail-out of the auto industry, Mr Mourdock sued to stop it, arguing (correctly) that bondholders, including several pension funds for state employees in Indiana, were getting a raw deal.

It was Mr Mourdock's campaign against the auto bail-out that first caught the attention of the Republican pressure groups that have latched on to the tea party. They spent generously on his behalf. The Club for Growth, which pushes laissez-faire economics, devoted $1.7m to advertising and flyers, and funnelled another $300,000 in donations directly to Mr Mourdock.

Democrats hope this investment will prove counter-productive. They point to polls showing their candidate, Joe Donnelly, faring much better against Mr Mourdock than he would have against Mr Lugar. In several Senate races in 2010 Republicans in effect forfeited seats they could have won by nominating unpalatably conservative candidates. But Indiana is a Republican-leaning state, and Mr Mourdock does not project an air of extremism. He is appealingly sober and self-effacing on the stump—always going out of his way, for example, to pay tribute to Mr Lugar's long record of public service.

Whoever prevails in November, the Senate will have lost another moderate Republican. The New York Times has calculated that 78% of the more moderate half of the Republican caucus in the Senate in 2007 has left office, compared with just 39% of the conservatives. After this week, the few that remain will be more fearful than ever of a primary challenge from the right. That is a recipe, as Mr Lugar put it, for “an unrelenting partisan mindset” marked by “reflexive votes for a rejectionist orthodoxy and rigid opposition to the actions and proposals of the other party”. The results will be frustrating not just for the tea party, but for everyone.