On a Thursday evening at the end of August, a respectable, older crowd waited in the ballroom of the Double Tree in Wilmington, Delaware, to hear Jim DeMint speak. The dashing former South Carolina senator and Tea Party icon had been flying around the country on a private jet to stump for the cause of defunding Obamacare, and Wilmington was the last stop on his nine-city tour. In Dallas, he was joined by his protégé Ted Cruz, but most of the time it was just DeMint and his barker, Michael Needham.

In that Delaware ballroom, Needham, a dark-haired, square-jawed young man, dressed in a sensibly checkered button-down shirt and pleated khaki pants, was warming up the crowd. He strutted around the makeshift stage with the kind of robustness that masks a certain Washington stiffness. “Can we, in the month of September, achieve defunding Obamacare?” he boomed. “Yes, we can!” yelled the crowd.

Needham is the 31-year-old CEO of Heritage Action, the relatively new activist branch of the Heritage Foundation, the storied Washington think tank that was one of the leaders of the conservative war of ideas ever since it provided the blueprint for Ronald Reagan’s first term. Although DeMint is Heritage’s president, it was Needham who had designed much of the defund Obamacare strategy. Beginning in 2010, when Heritage Action was founded, Needham pushed the GOP to use Congress’s power of the purse to eviscerate the Affordable Care Act. He formed a grassroots army, which he used to keep congressional Republicans in line. “They make six hundred phone calls and have a member of Congress in the fetal position,” says one GOP congressional staffer.

After months of furious lobbying, Needham sold, at most, 20 members of the House on his plan of attack. In the end, this was enough to cement the party line—and lead the GOP to a spectacular, deafening loss.

Sorting through the wreckage, Washington conservatives can barely contain their anger at Needham for his ideological inflexibility and aggressive, zero-sum tactics. “Their strategic sense isn’t very strong,” griped a prominent Republican lobbyist. “They’ve repeatedly been wrong about how to handle this.” Says a senior House Republican aide, “Mike Needham played a large role in defeating ideas that would have worked out better.”