Many conservatives at the party's core weren't happy with Romney, and a line of would-be champions has auditioned for their support, including former House Speaker Newt Gingrich, former Minnesota Gov. Tim Pawlenty and Minnesota Rep. Michele Bachmann. But none of them succeeded in knocking Romney off his perch.
Perry's candidacy could be a flash in the pan, of course; voters have fallen in love with fresh faces before, only to reconsider as their flaws became apparent.
But Perry's surge is impressive, and there are reasons to believe he could win the nomination.
First, the polls. Last week the Gallup Poll showed Perry leading the field with support from 29% of Republican voters, with Romney at 17% and Texas Rep. Ron Paul at 13%. (Other surveys came up with similar results.) Perry's 29% was a stronger showing than Romney had enjoyed in most polls all year.
Though Perry is running strongest among conservatives, who make up a big majority of the GOP electorate, he has attracted a wider range of Republicans as well: high income and low income, college educated and blue collar, Northern and Southern. Some of Perry's support came from former Bachmann voters, but much of it came from voters who once preferred Romney — an ominous finding for the former front-runner, who still has a slight edge among moderates in the party.
Up until now there has been a hole on the right-hand side of the Republican field, and Perry appears to fit right into it.
He's a fervent fiscal and social conservative — unlike Romney, who started his political career as a relative moderate, especially on social issues, and has labored to establish right-wing credentials.
His rawboned Texas rhetoric, railing against Washington's "interference" in the affairs of small-town America, may frighten voters in the center, but it's right in tune with the "tea party."
He's a governor who can boast of his state's record of job creation — unlike Romney, Bachmann or anyone else in the race. (Yes, Texas got help from federal spending and the rising price of oil, and many of those jobs don't pay very well, but jobs are jobs.)
And he's a savvy, bare-knuckled campaigner who has won six contested statewide elections. Texas Democrats have long warned outsiders that they underestimate Perry at their peril.
"Running against Perry is like running against God," one of his former opponents, John Sharp, told Texas Monthly. "Everything breaks his way. Either he's the luckiest guy in the world or the Lord is taking care of him."
Perry has flaws, of course, beginning with his hair-raising rhetoric. He's condemned Social Security as a Ponzi scheme. He warned Federal Reserve Chairman Ben Bernanke that further monetary easing would be "almost treasonous" and said, "We would treat him pretty ugly down in Texas." And he has suggested that Texas could secede if it found federal actions intolerable.
Perry's candidacy is likely to deepen the cultural divide in American politics. He's been a strong opponent of gay marriage, although he says he'd leave it up to states for now. He says he doesn't fully believe in the theory of evolution, and he considers global warming a hoax.
Until now, Romney's campaign strategy has been to remain above the Republican fray and focus instead on President Obama, as if the nomination were already in the bag. Romney has avoided confronting any of his rivals directly to avoid anointing any of them as the one he fears most. It's a standard front-runner's strategy, but it only works if you're really the front-runner.
In the short run, Romney is likely to stay hunkered down, hoping for Hurricane Rick to blow over — ideally as a victim of his own Texas braggadocio. But if Perry can learn to talk like a presidential candidate, Romney will have to engage him one-to-one.
They'll both have a good opportunity in just nine days, when they meet on the same stage for the first time at a debate at the Reagan Presidential Library in Simi Valley.
On most issues, the policies Perry and Romney espouse are similar. They both stand for the GOP's articles of faith: lower taxes, less federal spending and less regulation of business.
But they represent two distinct styles of Republican conservatism: one rooted in the corporate boardrooms of the Northeast, with remnants of the business community's social moderation; the other rooted in the oil fields and town halls of Texas, no less friendly to corporations but far more eager to talk about Christian faith and struggles for the soul of the nation.
Other candidates are still in the race, of course, and more could jump in, including Sarah Palin.
But by the end of the evening on Sept. 7, if Rick Perry rises to the occasion, we might be looking at a two-man race.