Mitt Romney greets supporters at an election-night rally in Wisconsin: The former Massachusetts governor beat Rick Santorum 43 percent to 38 percent.

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itt Romney swept all three Republican presidential contests Tuesday, including the symbolically important Wisconsin, where he topped Rick Santorum 43 percent to 38 percent. In his victory speech, Romney ignored Santorum and his other two remaining GOP rivals, Newt Gingrich and Ron Paul, signaling that as far as he's concerned, a trio of wins in Wisconsin, Maryland, and the District of Columbia made him the nominee. Santorum, speaking from his home state of Pennsylvania, didn't take the hint, saying that with about half the delegates still up for grabs, it's still only "halftime" in the GOP contest. Most analysts put the GOP grudge match at the end of the fourth quarter, or later. With Wisconsin under his belt, has Romney essentially won the nomination?

Romney is now the indisputable nominee: Halftime? Only "Santorum would utter such preposterous lines" after his game-ending losses on Tuesday, says Jennifer Rubin at The Washington Post. At this point, "Romney is the undisputed choice of the Republican electorate." He beat Santorum among virtually all demographic and ideological segments, and the only real question left in this primary "is whether Santorum will get out before or after the Pennsylvania primary" on April 24.
"Romney puts it away, wins all three races"

Santorum might still play spoiler: In Wisconsin, "Santorum lost his last shot at a big, momentum-changing Midwestern win," says Maggie Haberman at Politico. But he's now the underdog in his home state of Pennsylvania, so beating Romney there could breathe new life into his struggling campaign. That won't put him any closer to winning the nomination — there's no way Santorum gets to the magic number of 1,144 delegates — but "he has a path to deny Romney 1,144 delegates," and that might be enough reason to keep fighting.
"5 takeaways from the primaries"

Romney won, but his big race is just starting: "Technically, there is still time on the clock," and Santorum can still pick up "some pyrrhic victories in the South," says John Dickerson at Slate. But let's be realistic: "It's over." Wisconsin was "merely a capstone on a [GOP] move to rally behind Romney." The presumptive GOP nominee won't get a victory lap, though. The general election starts now, and President Obama will be much harder to beat than Romney's weak field of GOP rivals.
"One race is over. Another begins."