Suggesting that a band of activists can topple the party establishment in presidential politics can seem foolhardy, even at a time when those same conservatives control the House. But Santorum and Newt Gingrich gave Mitt Romney a run for his money last year, even though both men were political has-beens when the primary season began. Cruz is a senator from the country’s largest conservative state, and he’ll have two more years of Senate action to keep himself in the limelight. If a Ted Cruz had been around in 2012, he arguably could have beaten Romney by giving conservatives a single charismatic candidate to rally around.

Already, Cruz’s no-compromise approach is working. His favorable ratings among tea-party Republicans have jumped from 47 percent to 74 percent since July—despite the negative attention of most mainstream media outlets, including the highly unusual decision of his home-state newspaper, the Houston Chronicle, to sharply criticize him. Traditionally, that would hurt a candidate. But not Cruz, and not for a tea-party base that feeds off media antipathy.

“While establishment folks will blame him for the shutdown, he will become a rock star for standing up and fighting the fight,” said Dave Carney, a senior strategist for Rick Perry’s presidential campaign. “When Ted Cruz ran for office, from the day he announced to the day he was elected, he always said he was going to defund Obamacare and stop Obamacare, and the fact is that he did exactly what he said he was going to do.”