Mitt Romney
Mitt Romney won Tuesday's Republican primary in Illinois. Reuters

Mitt Romney has won the 2012 Ohio Republican primary, passing Rick Santorum by a incredibly slim margin to take the state after a very tight race between the two candidates.

With 99.4 percent of the results in, Romney was declared the winner in Ohio with 38 percent of the vote, as reported by Politico. Rick Santorum placed second with 37 percent of the vote, Newt Gingrich ranked third with 14.6 percent, and Ron Paul, who neglected to visit the Buckeye state, received 9.3 percent of the vote.

Romney's Ohio win comes on the tail of victories in Idaho, Massachusetts, Vermont and Virginia, according to the Wall Street Journal, as Rick Santorum triumphed in North Dakota, Oklahoma and Tennessee, and Newt Gingrich won his native state of Georgia. The only state without a declared winner as of early Wednesday morning was Alaska.

Santorum's Pull With 'Reagan Democrats'

Rick Santorum had several advantages over Mitt Romney in Ohio going into Super Tuesday.

As a group, GOP voters who cast their ballots in Ohio were expected to be less wealthy, less educated, more likely to live in rural areas and more likely to be evangelical Christians than GOP voters in Michigan, according to Fox News -- all demographics that tend to favor Santorum over Romney.

Michigan, Romney's home state, was the site of a primary he should have carried easily. Instead, he barely managed to take the victory away from Santorum last week, edging the former Pennsylvania senator out by a mere three percentage points.

In that same state, Santorum beat Romney by 16 percentage points among Republicans earning less than $100,000 a year, where the share of voters is one point higher than it is in Ohio.

The share of people with no college education was also eight percentage points higher in the Ohio primary than in Michigan in 2008. Santorum beat Romney by six percentage points among that group in Michigan last week.

The share of rural voters relative to the state's total voting pool was three points higher in Ohio than it was in 2008. Santorum fared well in that category in Michigan.

Santorum also beat Romney by 16 percentage points in Michigan among evangelical voters. In Ohio in 2008, the share of voters who identified themselves as evangelical was five points greater than that in Michigan.

More important, however, according to Ohio Attorney General Mike DeWine, Rick Santorum was able to connect with Ohio voters in a way he felt Mitt Romney simply could not achieve.

Rick Santorum ... has a real connection I think to average Ohioans, DeWine told Fox News' Greta Van Susteren on Monday.

I've been with him as we have traveled around the state, time and time again, he added. His crowds have been two or three times as big as Governor Romney's ... There's a tremendous amount of energy in this campaign.

DeWine pointed out that many Ohio voters could be cast as Reagan Democrats, and he expressed serious doubts that Romney had the charisma to capture those voters.

I don't think he'll do well in the general election, DeWine said of Romney. I don't think he can reach out to the people we have in Ohio.

Mitt Romney: 'It's the economy, stupid.'

In the end, however, money was the crucial deciding factor in Ohio, both in terms of how much each candidate spent and the degree to which economic issues were a part of voters' decisions.

While both candidates spent a significant amount of time stumping in Ohio, Santorum was able to spend only $389,000 in the rust belt swing state. Mitt Romney, on the other hand, spent roughly $1.4 million, according to the NBC Super Tuesday guide.

Much of that money went toward getting the candidate's message out, but a good portion of it also went to face-time for the former Massachusetts governor.

As of March 1, the Romney campaign was outspending Santorum in TV and radio advertising in Ohio by a 6-to-1 ratio, according an analysis compiled by an anonymous Democratic advertising buyer.

But economic issues also factored into who Ohio voters chose to support, and here, Romney reigned supreme.

Ohio was one of the first states to be hit hard by the recession, but it was also one of the fastest to recover. Compared to Michigan, which has a 9.3 percent unemployment rate, Ohio has only 7.9 percent unemployment, below the national average.

Nonetheless, economic issues like balancing the budget proved far more crucial to most voters than social ones like a gay marriage amendment or prohibiting abortion.

A recent Suffolk University poll showed that Ohio voters placed more emphasis on economic issues than on social issues, with a ratio of 78 percent to 16 percent, respectively, and overall they considered themselves far more fiscally conservative than socially conservative.

This trend held especially true due to Ohio's open primary system, which allows independents and Democrats to vote in addition to registered Republicans, with the former two groups being far less likely to be socially conservative than their GOP counterparts.

A New York Times exit poll showed that, among voters across the two parties, Romney had succeeded in appealing not only to high-income, college-educated voters but to less-educated and less-affluent groups as well, though Santorum still had a slight edge among the poorer and less educated voters in the state.

Romney's success as a businessman has been among his chief talking points since the campaign began, as well as his handling of the Massachusetts economy as governor. That background helped him surge ahead by 17 points in Michigan among voters who considered the economy the most important issue in the race.

It is likely to be what contributed to his eventual success in Ohio as well, especially with independent voters and Democrats allowed to cast their vote.

I know the economy, Romney said while on a tour of Gregory Industries on Monday. I've been in it.

Romney's Ohio Win: The Delegate Issue

Symbolically, Ohio is a crucial state in the primary race. It is generally considered the most important one up for grabs in Super Tuesday 2012, especially after a month that saw Romney fighting Santorum for what was once his largely undisputed status as GOP front-runner.

No Republican has ever won the general election without winning the swing state first. The predominantly white, middle- and working-class families that make up much the state represent several key voting blocs for the GOP.

But the symbolism of Romney's Ohio victory was lessened by the fact that it took him so long to achieve the victory as the vote tallies were counted, and that he achieved it by so small a margin.

Luckily for him, Ohio's delegate count is also part of the prize, and a significant one at that.

This year, Ohio held a proportional primary, part of a move initiated by the Republican National Committee to avoid winner-take-all contests.

It was designed to drag out the primary process so it wouldn't end in South Carolina, former Ohio GOP Chairman Bob Bennett, who worked with the RNC to perfect the new delegate-selection rules, told the Dayton Daily News.

You wouldn't have a presumptive nominee after the first few states voted.

As a result, dividing the state's 66 delegates becomes somewhat more complicated than usual.

Fifteen of the state's delegates will be awarded through a formula based on the results of the popular vote. Three un-pledged delegates (high-level party officials like Ohio Republican Party Chairman Kevin DeWine) are allowed to support a delegate of their choice.

48 of Ohio's delegates, however, are split between the state's 16 congressional districts, and here, again, Rick Santorum's lack of organizational prowess has put him at a distinct disadvantage.

The former Pennsylvania senator failed to file a complete delegate slate. As a result, the candidate is ineligible to win as many as 16 of the 48 proportionally allocated delegates, meaning that even if he had won the popular vote in Ohio, he still likely would have lost out on a good portion of the delegates up for grabs in the state.

The whole dynamic has shifted. It's not about winning states. It's about winning delegates, Christopher Maloney, spokesman for the Ohio Republican Party, told the Daily News.

Santorum Backlash: 'He's not ready for prime time.'

That shift in the race doesn't help Rick Santorum, but it does help Mitt Romney.

Because he won in Ohio by such a slim margin, Mitt Romney's symbolic victory is not nearly so potent as it could have been, or indeed would have been just a month and a half ago. Along with a significant portion of Ohio's delegates, however, Romney will end Super Tuesday having proven that he has a chance, at least, to win the state in the general election.

That is the belief reflected in early exit polls, which showed that 42 percent voters, regardless of who they supported, believed that Mitt Romney would end up winning Ohio in November.

Rick Santorum's slip-up meanwhile, along with denying him delegates, provides fodder for the Romney campaign to show that Santorum is not a serious candidate in the race, something his campaign will need to downplay.

According to Romney's national counsel, Ben Ginsberg, Santorum's ability to field a full delegate slate in competitive state is a true test, especially for Republican primary voters to look at, whether a candidate is ready for prime time.

In the Fall, we know whoever the Republican nominee is will be going against one of the best, well-oiled political machines, Hamilton County Commissioner Greg Hartmann added in a statement to Talking Points Memo, noting that Santorum also failed to get onto the Virginia ballot for Super Tuesday.

This kind of ball drop at this stage of the campaign [also] shows he's not ready for prime time.