WORTHINGTON, Ohio -- As the candidates campaign almost nonstop in this most critical swing state, the presidential race has come down to a battle of two slogans: "Big Change" versus "Vote Early."

"We're going to see big change in November," Mitt Romney said Thursday, speaking to a crowd estimated at 3,100 on an unusually warm October afternoon in this suburb of Columbus. "This is an election about big things."

In contrast, the first thing Barack Obama did when he addressed a significantly bigger crowd -- 9,500 -- at a Dayton park Tuesday was to deliver the admonition: "Vote early. Do it now."

That's where the campaign is. Romney is pushing the same proposals -- repeal of Obamacare, the five-point plan to jump-start the economy -- but with the sense that everything looms larger and seems more consequential as the days tick down until Nov. 6. Obama, who has seen a semi-comfortable lead in Ohio shrink to something near a dead heat, just wants his supporters to get it over with.

While Romney tries to persuade, early voting has become the mantra of the Obama campaign, from the president down. On Thursday afternoon in Chicago, Obama sought to lead by example as he cast his own vote early -- a presidential first. Obama used the occasion to make a pitch for early voting, leaving the impression he flew Air Force One to Chicago solely for a photo-op urging his supporters to vote early.

The night before, Obama turned his appearance on the "Tonight Show" into a virtual commercial for early voting. "A lot of states now have early voting so you don't have to wait for Election Day," Obama said. "It means you don't have to take off work or try to figure how to pick up the kids." Obama later made an extended case for early voting, urging everyone to "make sure to take advantage of it."

The president is concerned with much more than voter convenience. Here in Ohio, for example, Obama won in 2008 in part because of a 20-point lead among Ohioans who voted early. John McCain actually won the votes cast on Election Day itself. Now, Obama is facing far stronger competition than McCain, and he is again trying to rack up a lead among early voters that will withstand a Romney win among votes cast on Nov. 6. Conversely, if Romney could cut into Obama's early-vote lead, he could very well overtake the president with a win on Election Day.

Obama officials sound confident. "In Ohio, early vote turnout is higher in counties that voted for Obama in 2008 than Republican counties," campaign manager Jim Messina told reporters on a conference call Tuesday. "Let me say that again -- in Ohio, early vote turnout is higher in counties that voted for Obama in 2008 than counties that vote Republican. That ... is a show of enthusiasm, but also strength."

Anecdotally, the Obama forces appear to be making progress. At Obama's rally in Dayton, more than half the people I spoke to had already voted. Others said they intended to vote in the next few days, or at least before Nov. 6. At Romney's gathering in Worthington, no more than one in four had already voted. Most said they just preferred to cast their votes on Election Day itself.

In the big picture, however, Romney officials dispute virtually everything Team Obama says. In a strategy memo released Thursday, the campaign's national political director, Rich Beeson, and Ohio state director Scott Jennings argued that Republicans have made huge gains. "The [Romney] voter contact operation far exceeds what was done on the ground in 2008," they wrote, "and there are signs the ramped-up volunteer efforts are having an impact on early voting, seriously slicing into Obama's 2008 margin of victory during the early period."

"The main deal is the margin," Jennings explained as he waited for Romney to appear in Worthington. "We think it's gone from about a 20-point victory for them in early voting in '08 to about six points now. If they beat me by six in early voting and I beat them by 13 on Election Day, we're going to win the race."

At this point, the polls seem almost irrelevant as the candidates run two different races. For Romney, it's all about "Big Change." For Obama, it's "Vote Early."

By the way, Mitt Romney plans to vote the old-fashioned way, in person on Election Day, in Belmont, Mass.

Byron York, The Examiner's chief political correspondent, can be contacted at byork@washingtonexaminer.com. His column appears on Tuesday and Friday, and his stories and blogposts appear on washingtonexaminer.com.