Rick Santorum roared back to life with his first victories since the snows of Iowa on Tuesday, racking up a triple triumph in the Missouri primary and the Minnesota and Colorado caucuses.

Campaigning with little visibility and less money, the former senator crushed Mitt Romney in Missouri’s beauty contest, and almost no one expected him to add Colorado to his win column.

The question is whether Santorum’s strong showing revives his candidacy—enabling him to elbow aside Newt Gingrich as the conservative alternative to Romney—or just gives him ephemeral bragging rights that will vanish with the next news cycle.

It was an unambiguous setback for Romney, especially in Missouri, where he was headed for just a quarter of the vote despite that fact that Gingrich didn’t qualify for the ballot.

In an unusually animated speech in Missouri, Santorum tried to link his chief rival to the man he hopes to oppose in the fall. On Wall Street bailouts, health care, and cap and trade, he said, “Mitt Romney has the same positions as Barack Obama.” Santorum took a series of populist swipes at the president, saying, “He thinks he’s smarter than you” and “He thinks he knows better how to run your lives.”

Santorum, a Catholic, also delivered a faith-based message, saying that unlike when “God gives you rights,” the government can take rights away. He accused Obama of trying to “impose his secular values” by requiring organizations to offer birth control in health-plan coverage regardless of religious beliefs, a position strongly opposed by many Catholic leaders.

The Romney camp knew it was going to have a bad day. That’s why it sent out an advance damage-control memo in the morning from political director Rich Beeson, declaring that “no delegates will be awarded on Feb. 7.” That’s true, but, um, the same was true in Iowa’s outsize caucuses.

What’s more, Beeson wrote, “there is no way for any nominee to win first place in every single contest—John McCain lost 19 states in 2008, and we expect our opponents to notch a few wins too. But unlike the other candidates, our campaign has the resources and organization to keep winning over the long run.” Nothing to see here, move along.

But it can’t be a good sign for a frontrunner who had everything going for him—money, media attention, ground troops, and a widespread belief that he’s got this thing wrapped up—to be upended by an underfunded challenger.

Santorum, who lost his Pennsylvania seat in a blowout six years ago, deserves credit for sheer doggedness. It’s been hard at times to remember he was still in the race, especially after Gingrich won South Carolina. In Florida, Gingrich openly suggested that Rick step aside so conservatives uneasy about Mitt could unite behind a single challenger. Now that argument might be turned on its head, since Santorum has none of Gingrich’s personal baggage or the scars from his 1990s tenure as House speaker.

If Santorum’s big night brings him a major boost in fundraising, it could change the complexion of the race. He has simply been unable to compete on the airwaves with his shoestring campaign. He is certain to draw more journalistic scrutiny as well, which could bring a renewed focus on his stance against abortion and on other social issues.

The Romney camp took Santorum seriously enough to mount a series of attacks on Monday, led by former Minnesota governor Tim Pawlenty. A lot of good that did him.

If Santorum seemed to fly under the radar en route to Tuesday’s triumphs, that’s because news organizations have sent few reporters to the three western states and were treating the race itself as a two-man contest between Romney and Gingrich. It’s déjà vu all over again: the media pretty much ignored Santorum in Iowa until he surged in the final weeks to win the caucuses by 34 votes, or whatever it was, after appearing to lose by eight.

Santorum’s weaknesses as a candidate were on display when he tanked in New Hampshire, South Carolina, and Florida. He is not a charismatic speaker and often drones on about ancient legislative details. Even as his debate performances improved, he seemed overshadowed by Gingrich and Romney.

Now the pressure switches to Newt. If he goes 0-for-February, despite being a national figure for two decades, what is his rationale for staying in a race where Santorum seems increasingly viable?

Without taking anything away from Santorum, Tuesday’s results showed that Mitt Romney, who would like to switch to general-election mode, still hasn’t sealed the deal with Republican voters. The conservative unease with the former governor has not faded. And the longer the slog continues, the better the news for Barack Obama.