WASHINGTON -- Escalating an increasingly acrimonious campaign, Republican presidential challenger Mitt Romney dug in Wednesday on his charge that President Obama's campaign was being driven by "division and attack and hatred" and called on the president to lift the tone of political discourse.
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.
Obama campaign spokesman Jennifer Psaki said Romney's comments once again seemed "unhinged." The Democratic campaign had a similar response Tuesday night when Romney first accused Obama of running a campaign of "hate."
Romney shot back: "I think unhinged would have to characterize what we've seen from the president's campaign."
"These personal attacks, I think, are just demeaning to the office of the White House," he added.
The campaign has been lurching toward a more intensive stage in the wake of Romney's announcement Saturday of conservative Rep. Paul Ryan of Wisconsin as his vice presidential running mate.
Even before that, both campaigns and independent groups supporting them had been running increasingly provocative TV ads.
Priorities USA Action, a group supporting Obama, ran a commercial suggesting 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 Romney campaign is running an ad, widely discredited by independent fact-checkers, that accuses Obama of gutting welfare reform. Romney's team is also running an ad that criticizes Obama for raiding the Medicare trust fund, a charge the president's team labeled dishonest and hypocritical.
The tone 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, Biden said he had meant to use the term "unshackled." But he did not apologize, and he mocked the Romney campaign for showing outrage.
In his interview Wednesday on "CBS This Morning," 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," he said.
Romney was holding private fundraisers Wednesday in North Carolina and Alabama. The president 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.
Obama's campaign was also 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.