(CNN) -- In a year when electability consistently tops Republican primary voters' lists of candidate qualities, Mitt Romney has made the sale. In contest after contest, he's generally chosen as the contender most likely to beat President Barack Obama in November.
On Tuesday, voters in Ohio agreed: They thought he was roughly twice as electable as Rick Santorum, according to exit polls.
But if Romney has primary voters' heads, Santorum seems to be reaching their hearts.
Romney may have made up some ground with working-class voters, but Santorum held the advantage on the question of which candidate "best understands the problems of average Americans." He held it in the working-class battleground of Ohio; he held it in the evangelical stronghold of Tennessee. He didn't capture it in Vermont, where Romney scored a major win Tuesday; there, the title went to ... Ron Paul.
Still, Romney was the night's biggest winner.
As expected, Romney earned victories in home state territory with higher-than-average percentages of political moderates, like Massachusetts and Vermont; in Idaho, home to one of the nation's largest Mormon populations; and in Virginia, where his only rival to make the ballot was Ron Paul. He continued his strong showing with college-educated, wealthier voters, and seniors. But other key trends broke in his direction as well.
In recent contests, late momentum has tended to favor Santorum. Not Tuesday: Romney evened the playing field, with both candidates drawing roughly equal proportions of both early and late deciders in Ohio.
Then there was the gender breakdown. On first glance, there wasn't a major split: as in prior contests, men -- who made up a majority of Ohio's Republican primary voters -- favored Santorum, while women favored Romney.
But breaking down the numbers still further: Rick Santorum had a 5-point edge among all Ohio voters combined, male and female -- except for the working women who made up around a fifth of the state's electorate today: Those voters gave Romney an 8-point edge. Romney continued to show strength with Catholic voters; virtually across the board, they supported him over fellow Catholic Rick Santorum. Even in Georgia, where home state candidate Newt Gingrich, also a Catholic, won a decisive victory, Catholics still backed Romney.
Romney also walked away with the night's biggest prize, Ohio. Still, should he become his party's nominee, exit polls hint at some hurdles in the fall.
Once again, the conservative base -- white evangelicals, strong supporters of the tea party movement, voters who believe abortion should always be illegal, and those who say the religious beliefs of candidates matter "a great deal" -- backed Santorum over Romney by significant margins in Ohio, as in other competitive states.
Romney captured independents in his home state of Massachusetts, but struggled to win them over virtually everywhere else. In open primary states with significant numbers of independent or Democratic voters, Ron Paul was the top pick for those blocs. In Ohio, Santorum took that title.
Santorum joined Romney on the losing end of one key stat in Ohio: More of their votes there came from people who still hold reservations about them than from strong supporters.
But an even more troubling number for Romney in a swing state that has historically been a required win for any successful Republican White House hopeful: Only six in 10 Santorum voters said they'd definitely back the GOP nominee no matter what. That's a good chunk of the GOP electorate -- and as Rick Santorum himself learned Tuesday, in Ohio, the slimmest margins can make all the difference.