Mitt Romney Takes Wisconsin, Two Other Primaries

Mitt Romney won the Wisconsin GOP primary and a pair of other nominating contests on Tuesday, further cementing his status as his party's likely presidential nominee.

Fox News called the Badger State for the former governor shortly before 9:30 p.m. ET, roughly a half hour after the polls closed there. CNN followed suit moments later. Earlier Tuesday, the networks declared Romney the winner of the Republican primaries in Washington, D.C. and Maryland.

Romney entered the evening as the clear favorite in all three contests, although Rick Santorum had made a concerted push to compete in Wisconsin. Ultimately, his efforts there came up short, casting further doubts on whether he'll be able to derail Romney's mathematical march to his party's nomination. Nonetheless, the former senator declared the race only half over Tuesday night and promised to press on.

According to early exit polls from CNN, Romney earned 43 percent of the vote in Wisconsin, outpacing Santorum's 35 percent by 8 points. Ron Paul and Newt Gingrich placed third and fourth, with 11 and 6 percent, respectively, according to the survey.

Romney entered the night with a lead of more than 7 percent in recent state polls in Wisconsin, which was widely considered to be the night's biggest prize. Still, Santorum supporters had surprised pollsters before this campaign season by delivering more votes for the social conservative than surveys suggested they would, a trend that kept alive the possibility of an upset win—or perhaps more likely simply a closer-than-expected finish—ahead of the Badger State returns.

Regardless of the final vote tallies, two things appear certain: 1) Romney will increase his already sizeable delegate lead over Santorum, and 2) that fact won't force Santorum to drop out of the race, despite a growing chorus of GOP establishment figures calling on him to do so.

Still, most observers now predict that Santorum will face a must-win contest before the month is out in the form of Pennsylvania's April 24 primary, a prediction that was underscored by the fact that the former senator was already campaigning in his home state when the polls closed in Wisconsin.

"We have now reached the point where it's halftime; half the delegates in this process have been selected," Santorum told a crowd of supporters before asking: "Who's ready to charge out of the locker room in Pennsylvania for a strong second half?"

In the lead-up to Wisconsin, Santorum had hinted at the possibility of a string of likely losses this month and suggested he'd forge ahead nonetheless. "We knew April would be very tough for us," he told CNN's Piers Morgan on Monday, before looking ahead to next month's contests in more conservative states like Texas and North Carolina. "This is a very close race and by the end of May, we expect this race to be very close to even."

We'll have to wait for the final state tallies before we know exactly how the delegates from Tuesday's contests will be divvied up. Still, Romney is certain to bolster his already commanding delegate lead when all is said and done. Slate's David Weigel has a look at the math and shows us how.