Today’s high-profile Republican contests in Arizona and Michigan are the biggest test of Rick Santorum’s staying power since beating Mitt Romney in Colorado, Missouri and Minnesota earlier this month. None of those contests included exit polls, but today’s contests will, offering a fresh glimpse of what’s on voters’ minds. We’ll be live-blogging on the exit polls tonight on the Post’s Election 2012 blog, and tweeting results @postpolls.

Here are five key factors to watch in tonight’s exit poll results.

Will strong conservatives sink Romney?

Conservative voters nationally are souring on Romney, according to a new Washington Post-ABC News poll, and Romney struggled among “very conservative” voters in Florida, South Carolina and Iowa. The question for Tuesday’s contests is how many staunch conservatives will show up to the polls, and whether Romney can compete with Santorum for their votes.

“Very conservative” voters made up just about a quarter of primary voters in Michigan’s 2008 Republican primary, low compared with other contests this cycle. Strong conservatives accounted for three in 10 voters in the 2008 Arizona primary.

Santorum dominated Romney by nearly 3 to 1 among very conservative voters in an NBC News/Marist Michigan poll released last week. In Arizona, Santorum edged Romney 38 to 33 percent.

‘Dirty trick’ Democrats could make a difference

Michigan is an open primary that allows any registered voter to select a Republican ballot, a potentially bigger factor this year with no competitive Democratic contes. Santorum looks to capitalize on this process quirk, commissioning robo-calls to Democrats attacking Romney and seeking their votes. (Romney accused Santorum of playing a ‘dirty trick’.) Some Democrats may have more nefarious motives, looking to deny Romney a win that could help clinch the nomination.

The exit poll will tell just how much a factor crossover voting plays. Democrats made up only 7 percent of Republican primary voters in 2008, as there was a contest on their own side as well. Romney’s appeal among moderate to liberal primary voters this year should give him a natural advantage among Michigan Democrats. But if they show up in droves with a mission to deny Romney a win, they could tip the scales in favor of Santorum.

Will class divide appear?

Santorum’s ‘Snob’ volley at President Obama represents a clear effort to win over working class voters and capitalize on perceptions that Romney is out of step with their concerns. Class divides played a supporting role in Gingrich’s South Carolina win – he beat Romney by 19 points among voters lacking college degrees, but by a smaller 6 points among those with college diplomas.

Santorum has yet to connect strongly with these voters at the ballot box, at least in contests where exit polls are available. In Iowa, Santorum won 26 and 23 percent of college and non-college voters alike.

Santorum’s electability may hold him back

Primary voters have honed in on beating Obama as the top candidate attribute, a glaring weakness for Santorum so far this cycle. Just 4 percent picked Santorum as the contender with the the best chance of defeating Obama in a Post-ABC poll earlier this month.

Santorum peformed well in Iowa while losing electability-focused voters in a landslide to Romney. In Michigan he needs to hold his own among these voters, or hope his appeals to conservative values and the working class will lessen the focus on who can beat Obama.

Where do Arizona’s Hispanics stand?

Romney pushed back perceptions that he has trouble with Hispanic voters after winning an outright majority of this group in the Florida primary. Hispanic voters in Arizona lack strong ties to Cuba and may have a different outlook on the candidates’ positions on immigration, having experienced first-hand the state’s immigration enforcement law passed in 2010.

Hispanics play only a small role in Republican primaries, but they will be critical in the general election against Obama. Arizona may offer clues about which, if any, GOP candidate will compete with Obama for Hispanic voters. In 2008, Hispanics made up 7 percent of GOP primary voters in Arizona.

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