After surviving this weekend's presidential debates, Mitt Romney appears set to cruise to victory in Tuesday's New Hampshire primary. (New York Times stats guru Nate Silver calculates that Romney has a 98 percent chance of winning the Granite State.) If so, history suggests he'll go on to face Obama: No modern presidential candidate has ever won in Iowa and New Hampshire and failed to be crowned nominee. But critics continue to point out that Romney has a whole lot of trouble winning over more than a quarter of the GOP electorate and question whether he really has the nomination wrapped up. Here, four ways Mitt the inevitable could still lose the GOP race:

1. Romney loses New Hampshire, then implodes

"Those looking to stop a Romney coronation" in New Hampshire can draw hope from the large number of voters still casting about for a Republican to back, says Chris Camire in the Fitchburg, Mass., Sentinel and Enterprise. The Granite State could easily "break late for another candidate," and "a loss or even a narrower-than-expected win for Romney could tarnish his aura of inevitability." Sometimes "inevitability can be a curse" — just ask Hillary Clinton, says Michael Brendan Dougherty at Business Insider. And if, against all the odds, Mitt loses New Hampshire, expect "pandemonium" and a lot of "Republican big-wigs" jumping off the sinking Romney ship.

2. Santorum catches fire, then unites the anti-Romney faction

Romney will win New Hampshire, but he "won't beat the expectations spread," says Jonathan Alter at Bloomberg View. That means he'll limp on to the next bunch of states, starting with South Carolina, which favors a Tea Party–friendly social conservative like Rick Santorum. Indeed, Santorum is the most likely "ABM (Anyone But Mitt) candidate" to unite conservatives and trounce Romney on March 6's Super Tuesday, when a dozen states vote. "Don't be shocked to see [Santorum] accept the nomination late this summer." Romney is "desperately seeking enthusiasm" from the "white voters without college educations" who make up the GOP base, while Santorum is actually from that group, says George Will in The Washington Post. "Who is more apt to energize them"? If he can raise cash online, "Santorum can hope to win the nomination."

3. Ron Paul and Co. force a brokered convention

Santorum may not win outright, but "the probability is growing that we will see a brokered Republican convention in Tampa next August," says Philip K. Chapman at The Patriot Post. Thanks to the GOP's new proportional allocation system, no candidate is likely to get enough delegates to win outright. "If a multi-ballot battle erupts at the convention, the Republican Establishment will try to negotiate nomination of some lackluster pale-pastel RINO" like Romney, but well-organized conservatives can beat them on the floor. The key will be Ron Paul, says Dustin Krutsinger at Caffeinated Thoughts. With his steady accrual of 10 to 30 percent of each state's delegates, never-drop-out Paul will emerge as a "kingmaker," and Romney may not end up with the crown.

4. Another candidate joins the race

Don't forget "the wildcard option," says Erick Erickson at RedState. There's still time for someone like Louisiana Gov. Bobby Jindal to dive in. It's too late to get on the ballot in some states, but looking at a list of states you can still file to run in, and how many delegates they have, it's clear that a popular small government conservative still has time to "enter the race and, if the candidate sweeps the states, win outright," or at least help force a brokered convention. It's not over till it's over.