'I really believe we are in a great position right now," says Michael Needham, the 31-year-old president of Heritage Action, the lobbying arm of the nation's largest conservative think tank. By "we" he means the Republican Party and the conservative movement; their "great position" refers to the potential to win the political battle over the government shutdown.

Though Texas Sen. Ted Cruz is the public face of the high-risk strategy to "defund" ObamaCare, the masterminds behind it are a new generation of young conservatives, chief among them Mr. Needham. From a tactical view, the strategy has been deployed with precision. In August, only Mr. Cruz and a band of renegade tea-party Republicans in the House favored this approach, and the media collectively scoffed. But by September, House Republicans couldn't pass a budget without attaching the defunding rider that has grounded much of government.

"We rallied the conservative grass roots across the country," Mr. Needham says, and ran ads in more than 100 districts on the health law. It worked. During the August recess, these activists demanded that their members of Congress stop ObamaCare.

To most observers, who think the GOP is losing this fight, Mr. Needham's optimism that Republicans will carry the day may seem astonishing. But Mr. Needham says the second-guessers are wrong.

"We just spent the last three months talking about nothing else but ObamaCare. It has been on the front page of every newspaper. The polls show ObamaCare's more unpopular than ever. People are starting to wake up that it isn't going to work at all," he says. "Even Jon Stewart of 'The Daily Show' is making fun of the law." On Monday, Mr. Stewart had Health and Human Services Secretary Kathleen Sebelius as a guest, Mr. Needham notes, and the host "bet that he could download every movie ever made before she could log on to the ObamaCare website."