It’s going to be a long hard slog. Mitt Romney won the Arizona and Michigan battles but he is far from winning the nomination war. The primary obstacle course will wind deep into the South, halting any of Romney’s momentum from his weak wins this week, as Ben Adler notes. The elections then enter the home stretch, beginning with Texas’s late May primary with 155 delegates. Here is where Romney could make his last stand and go down fighting.

There are four more months of primary elections and there are still 2,002 delegates up for grabs. To begin, Super Tuesday is not that super, with only 437 delegates at play. Delegate distribution will be interspersed throughout the contests, with the last month of the primary election season seeing 494 delegates in play. Almost one-third of these delegates will be from Texas, and Texans are not that sweet on Romney. According to the latest University of Texas/Texas Tribune poll, Romney is the choice of only 16 percent likely Texan voters, coming in third after Gingrich, who is at 18 percent, and Santorum, at 48 percent. Because of the number of delegates, the late date and Santorum’s overwhelming lead, the Lone Star state could be a game-changer.

Romney is the weakest candidate among Southern evangelicals. The magnitude of his weakness will become painfully obvious with the series of Southern primaries that are held in May: North Carolina, West Virginia, Arkansas and Kentucky. According to a study conducted at the beginning of 2012 by political scientists John Geer and Brett Benson at Vanderbilt and Jennifer Merolla at Claremont Graduate, Romney’s faith continues to be his Achilles heel in the South. While there is still a generalized anti-Mormon sentiment, in the GOP—about 20 percent—that figure jumps up to 31 percent among Southern evangelicals.

Geographically, Texas is considered both a Southern and a Western state. Religiously, however, it is more similar to its neighboring Southern states. Evangelicals account for one-third of the population and close to half of the electorate. And 31 percent of Texan voters do not believe Mormons are Christians. Texas’s religious and social conservatism bodes well for Santorum. This same conservatism is what likely makes Gingrich’s peccadillos too much for Texans to handle from a non-native son.

If Santorum picks up momentum in Texas at the end of May, he positions himself well for the June 5 California primary with 172 delegates. The RealClearPolitics polling average for the California primary has Romney ahead at 32 percent, with Santorum at 28 percent. California could be especially good for Santorum, since it is unlikely that he would have to give up much of the conservative vote to Gingrich.

Texas will cap off the Southern primary elections, where Santorum’s brand of conservatism and Romney’s Mormon faith could prove a dangerous combination for Romney. Timing is everything, and for Santorum the timing of Texas’s primary is on his side. Redistricting litigation prevented the Texas primary from being held during its original Super Tuesday date. Had the Texas primary come on the heels of Romney’s wins and early delegate lead, then he likely would not find himself making his last stand in Texas.