CINCINNATI — President Obama, seeking to shore up support among women, intensified his pressure Thursday on Mitt Romney to break ties with a Republican Senate candidate who said that if a woman becomes pregnant from rape it is "something God intended." Romney ignored the issue, holding to an optimistic campaign tone as he fought for victory in crucial Ohio.

Obama, wrapping up a 40-hour battleground-state blitz, also headed to his hometown of Chicago and cast his ballot 12 days before Election Day. He voted for himself, the first time an incumbent president has voted early. He implored supporters to do the same.

Thirty-five percent of all voters are expected to cast early ballots, up from 31 percent four years ago, according to Paul Gronke, director of the Reed College Early Voting Information Center in Oregon.

Republicans were equally eager to turn out the vote. "I need you to commit as well, not only to vote, and vote early — I won't say often, just vote early," Romney urged a Cincinnati crowd.

Early voting matters because it helps increase turnout and "frees up a lot of resources that can be used to get more voters to the polls (on) Election Day," said Larry Sabato, director of the Center for Politics at the University of Virginia.

The 2012 presidential contest topped the $2 billion fundraising mark Thursday, putting the election on track to be the costliest in history.

It's being fueled by a campaign-finance system vastly altered by the proliferation of "super" political-action committees that are bankrolling TV ads in closely contested states.

On the campaign trail, the president made repeated, though indirect, references to Indiana Republican Senate candidate Richard Mourdock's comment on rape and pregnancy.

"We've seen again this week, I don't think any male politicians should be making health-care decisions for women," Obama told a crowd of about 15,000 in Richmond, Va. The president's aides pressed further, using a Web video to highlight Romney's endorsement of Mourdock and to accuse the GOP nominee of kowtowing to his party's extreme elements.

Romney, who appears in a television advertisement declaring his support for Mourdock, brushed aside questions on the matter throughout the day.

He focused instead on turning his campaign's claims of momentum into a more practical way to win the required 270 Electoral College votes. Ohio is crucial to that effort.

"This election is not about me," Romney told 3,000 people at a southern Ohio manufacturing company. "It's not about the Republican Party. It's about America. And it's about your family."

To an estimated 12,000 people at a high-school football stadium in Defiance, Ohio, he said late Thursday: "We have a big election, and we want a president who will actually bring big changes. And I will and he won't."

Romney has disavowed Mourdock's comments, but his campaign says he continues to support the Indiana Republican's Senate candidacy.

Less than two weeks from Election Day, both candidates feverishly campaigned across the country in an exceedingly close race.

Obama advisers insist they've lost no ground with women. But their eagerness to highlight Romney's connections to Mourdock indicated some degree of nervousness within the campaign.

Romney's campaign reached out to female voters Thursday by sending Ann Romney on daytime's "Rachael Ray" show, where she prepared her meatloaf-cakes recipe and took cameras along on a trip to Costco to shop in bulk for family gatherings. Mrs. Romney said that, with 30 mouths to feed, her family always eats buffet-style and that "Mitt is often at the front of the line."

The Republican presidential nominee also faced fresh scrutiny of his business record Thursday after the release of newly unsealed testimony related to Staples founder Tom Sternberg's divorce. Documents show Romney said he was initially skeptical of the idea for Staples, the office-supply chain he lauds as a business-success story that he helped create.

Romney also acknowledged in testimony in Massachusetts probate court in 1991 that he and other Staples directors created a special class of company stock for Stemberg's then-wife as a "favor" to Stemberg, who was a speaker at the August Republican convention.

Throughout the campaign, Romney has described Staples as a "great American success story" and took credit for its growth to a mega-firm employing nearly 90,000 workers.

Robert Jones, an attorney for Romney, rejected the notion that Romney undervalued Staples stock to help Stemberg.

Obama's campaign also trumpeted the endorsement by former Secretary of State Colin Powell, a Republican who supported Obama in 2008. Powell praised Obama's handling of the economic recovery, telling "CBS This Morning," "I think we've begun to come out of the dive and we're gaining altitude."

Elsewhere Thursday, GOP vice-presidential nominee Paul Ryan showered attention on Virginia, telling voters in Appalachian coal country that winning a close race won't be enough for the GOP ticket.

"The worst thing that could happen is President Obama gets re-elected and we have more of the same with a debt crisis," Ryan said. "The second worst thing that could happen is we get elected by default, without a mandate."

Vice President Joe Biden took time off the campaign trail to attend a prayer service for former Democratic Sen. George McGovern.

Material from McClatchy Newspapers is included in this report.