The story of Donald Trump’s doomed campaign has been replaced by the story of his inevitability as the Republican nominee.

It’s a sea change indicative of his constant ability to defy expectations. He placed second in the nation’s first contest in Iowa, went on to dominate in New Hampshire and South Carolina, and won Nevada’s GOP caucus on Tuesday night.

But it’s not Trump’s past wins that foretell doom for any Republican candidate trying to stop this phenomenon. It’s the fact that a week out from Super Tuesday, Trump is the overwhelming favorite to win most of the remaining voting states—and their delegates—across the country. To clinch the nomination before the Republican convention, Trump needs 1,237 committed delegates. Before Nevada, he had 67 delegates, and Ted Cruz was in second place with 11.

Here’s how the math works.

On Super Tuesday alone, the only states that Trump currently risks losing, according to Real Clear Politics averages, are Arkansas and Texas. And both of those states have Cruz leading by surmountable percentages (note, though, that polling in both states is not always frequent or entirely current).

Even if Trump comes in second in Texas, he could still win.

Texas is a state that is typically proportional in its delegate allocation but has what the website Frontloading HQ calls a “trigger,” which creates a condition in which the state becomes winner-take-all. This would happen if a candidate wins a majority of the vote. Should this overwhelming victory not happen for Cruz, and, say, Trump comes in second in a proportional setting, the senator from Texas must cede a portion of the 155 delegates in play, thereby essentially handing the contest and the nomination to Trump. If Cruz can’t win his home state, he has little chance throughout the rest of the spring.

The Republican primary contest has long had what Sam Wang, a Princeton University professor and neuroscientist, refers to as a “deadline problem.” Wang, who runs the Princeton Election Consortium, posited on Feb. 11 that the Republican field needed to get smaller in a hurry, setting two specific deadlines to try to defeat Trump.

The first deadline is Feb. 29, at which point Wang thinks there need to be only two alternatives to Trump prior to March 1 voting. The second is March 14, when Wang thinks there can be only one other option besides Trump.

The issue is that many of the states leading up to March 8 fit the model of Trump’s South Carolina victory, in which he captured about a third of the vote but still managed to get all the delegates due to proportionality rules.

Even after Jeb Bush dropped out of the race following his defeat in South Carolina, Trump still faces four opponents before March 1. Marco Rubio, John Kasich, and Cruz will all try and see if they can win their respective home states (where all of them except Rubio are leading). Ben Carson has stubbornly stayed in the race despite finishing fourth at best in most states. But he could be out if his campaign contributions dry up in the coming weeks.

This means that unless everyone but Rubio and Cruz quits in the next week, Trump can’t be caught.

“Any talk of stopping Trump is highly unrealistic,” Wang told The Daily Beast. “Nearly all analysts, including data pundits, are blinded by the peculiarity of Trump’s campaign.”

Wang said he thinks Rubio has no chance of locking up the nomination anytime soon because the field is too divided for him to corral a lot of delegates by Super Tuesday. And if the senator loses his home state of Florida, which polling suggests he might, there isn’t enough time to make up the delegate difference before the Republican convention in July.

Josh Putnam, a political science professor at the University of Georgia who runs Frontloading HQ, told The Daily Beast that the only scenario that would allow a Trump defeat in the primary is a one-on-one matchup.

“If only Trump is winning, then no one can catch him in the delegate count,” Putnam said. “The only play in that scenario would be for opponents to either drop out or play to keep Trump under the 1,237 delegate majority needed to clinch the nomination on the first ballot at the national convention.”

One state that could slow Trump’s speeding train is Ohio, whose winner-take-all contest could keep him shy of the delegate count necessary to clinch the nomination. Trump sits atop the polls there, narrowly beating Buckeye Gov. Kasich.

Even in a situation in which Trump, Rubio, and Cruz are the last three standing, as conventional wisdom would suggest, the road still looks rocky for Cruz and Rubio. An Economist/YouGov poll taken last week showed Trump with 46 percent of the vote, Rubio with 28 percent, and Cruz with 26 percent. An earlier NBC/Wall Street Journal poll found Trump leading in the same circumstance.

Also, as saliently noted by Sahil Kapur in a Bloomberg Politics piece, as of January, Trump had a higher share of Republican voters who would consider voting for him than Mitt Romney had in 2012 around the same time. This suggests the mythic establishment lane has been almost entirely consumed by the singular Trump lane.

Rubio, the presumed second-place candidate at this point, cannot merely rely on absorbing Bush’s supporters either, as ideologically those supporters could just as easily go with Kasich as Rubio. In fact, the only way the Florida senator could catch the frontrunner is to siphon off some of Trump’s support, which seems unlikely. In a January NBC poll, 51 percent of Trump supporters said they were absolutely sure of their choice, while only 26 percent said the same for Rubio.

Wang says the question of Trump’s “ceiling” in terms of national polls is worthless. The real question is just how high his delegate count can go.

“Under Republican rules, it is possible to win a majority of delegates with as little as 30 percent of the vote, if conditions are right,” Wang said, using South Carolina, where Trump took all 50 delegates with only 33 percent of the vote, as an example. “That involves a split field, which is why I have been so focused on that. At Trump’s current level of support, about 35-40 percent, his delegate ceiling is above 50 percent,” meaning, according to Wang’s model, that even if Trump garners 35 percent of the popular support, he can still earn at least half of all the national delegates available.

As for Rubio, the blunt question is, what state can he win on Super Tuesday? He led by a small margin in Minnesota and could see an opening in Colorado. But otherwise his chances look bleak.

In the fantasy scenario where Rubio is viewed as a possible foil for Trump, is it possible to still be a viable contender if you don’t win a state before March 15?

As Nevada’s caucus began, Rubio was getting ready to test this hypothesis with a slew of new endorsements in hand. But in an election where facts don’t matter and Trump is drowning out the noise, it’s going to take more than an impressive posse to catch the frontrunner—as Tuesday night’s results showed.