In an escalation of an increasingly acrimonious campaign, Romney went on national television to say he thinks Obama is "running just to hang onto power, and I think he would do anything in his power" to remain in office."
Interviewed on "CBS This Morning" from Columbus, Ohio, the former Massachusetts governor was asked if he was concerned people would think the presidential campaign has become "unhinged."
"I think unhinged would have to characterize what we've seen from the president's campaign," he replied. "These personal attacks, I think, are just demeaning to the office of the White House."
The campaign had been lurching into more heated exchanges in the wake of Romney's selection of conservative Rep. Paul Ryan of Wisconsin as his vice presidential running mate.
Even before that, independent groups supporting the respective campaigns had been running increasingly provocative TV ads, including one from a group supporting Obama. That commercial suggested Romney was personally responsible for the death from cancer of the wife of a man who worked at a steel plant that was bought and subsequently shut down by Romney's venture capital firm, Bain Capital.
The tone of battle reached a fever pitch Tuesday in connection with a remark Vice President Joe Biden made to a mostly black audience in Danville, Va. Commenting in response to Republican criticism that the Obama administration had sought to regulate Wall Street too tightly, Biden said the GOP wanted to "unchain Wall Street."
The vice president went on to say, "They're going to put y'all back in chains."
Speaking in Wytheville, Va., later Tuesday, Bidcen said he had meant to use the term "unshackled." But he did not apologize, and he instead mocked the Romney campaign for showing outrage.
In the interview Wednesday, Romney said, "I can't speak for anybody else, but I can say that I think the comments of the vice president were one more example of a divisive effort to keep from talking about the issues."
"The president's campaign is all about division and attack and hatred and my campaign is about getting Americans back to work and creating more unity in this country," Romney said.
Meanwhile, Obama's campaign on Wednesday is launching state-specific efforts to target elements of Ryan's austere budget proposals, expanding beyond its opposition to the Republican vice presidential candidate's Medicare overhaul.
The Obama strategy comes as Romney and Ryan make clear they plan to campaign aggressively on Medicare, not run away from it. In person and in a television ad, the Republicans argued Tuesday that Obama is the one who cut spending for Medicare to put money toward his divisive health care overhaul.
Obama was campaigning in Iowa on Wednesday, the final day of his three-day bus trip through the Midwestern swing state. First lady Michelle Obama was joining the president, marking their first joint appearance on the campaign trail since May. Romney had a pair of private fundraisers in North Carolina and Alabama.
Associated Press writers Kasie Hunt in Columbus, Ohio, and Jim Kuhnhenn in Washington contributed to this report.