Despite his string of southern victories, Republican presidential candidate Rick Santorum has yet to win one of the crucial Midwestern swing states.
The Wisconsin primary on April 3 may be Santorum's last chance to prove he can win such a state -- and that he's more than a regional or ideological candidate -- before the race shifts to the Northeast. There, front-runner Mitt Romney, a former Massachusetts governor, is expected to dominate.
"If he doesn't win Wisconsin, all the air gets let out of his campaign," Charles Jacobs, a political science professor at Wisconsin's St. Norbert College, told The Washington Examiner. "There are only so many swing states you can try to win, but then lose, before it becomes clear you are unable to win when it's important."
Santorum, whose campaign has caught on with conservative voters suspicious of Romney's politics, has twice come close to beating Romney in the industrialized Midwest, losing the Michigan primary by 3 percentage points and the Ohio primary by less than 1 percent. (RELATED: After Louisiana win, Santorum vows to stay in)
And while Santorum has blocked Romney from winning any contests in the Deep South, Southern states are more solidly Republican and deemed less critical for candidates trying to prove they have the broader appeal needed to beat President Obama in the fall election.
"If Santorum wins a Midwestern state, he can argue that his message is resonating with swing-state voters," Jacobs said.
A victory in Wisconsin, where the state's 42 delegates are going to be awarded by congressional district, won't do much to help Santorum narrow Romney's delegate lead. But it could pump new momentum into his campaign and bolster Santorum's argument for continuing in the race at a time when prominent Republicans, including former Florida Gov. Jeb Bush and Sen. Jim DeMint of South Carolina, are urging him to quit.
Santorum campaigned intensely in Wisconsin this weekend. While the state Republican establishment is preoccupied with an effort to recall Republican Gov. Scott Walker, Santorum focused on the evangelical voters in the northern part of the state, whose turnout could propel him past Romney.
Wisconsin has open primaries, which means Democrats and independents can vote in the Republican race. But turnout could be low thanks to the state's intense preoccupation with a planned June 5 vote to recall the governor, and that would help the candidate with the most motivated voters, say state political analysts.
In the 2008 primary, 38 percent of Wisconsin voters identified themselves as evangelicals, a relatively low level compared with the 70 percent-plus turnout by Christian voters in states Santorum has already won, including Oklahoma, Alabama and Mississippi. Santorum is also likely to do well in the western and central areas of Wisconsin, where voters in 2008 backed GOP presidential candidate Mike Huckabee, a conservative who placed second behind the eventual nominee, Sen. John McCain.
"Santorum certainly could win," Mark Graul, a Wisconsin GOP strategist, told The Examiner.
Still, Graul said, Romney's focus on the economy is likely to resonate more broadly with the Wisconsin electorate, who also see Romney as the candidate most likely to win the nomination. Romney, who needs 1,144 convention delegates to lock down the nomination, now has 560, far more than Santorum's 246.
"If Santorum wins or loses," Graul said, "I don't think that is going to change who the nominee is going to be."