DUBUQUE, Iowa (AFP) - Mitt Romney complained Wednesday that Barack Obama's re-election bid was steeped in "hatred" as the president accused his Republican foe of planning to slash state health benefits for the elderly.
Romney, hoping to turn Democrat Obama out of the White House after a single term, said that Obama and backers were stoking divides based on income, age and ethnicity, to whip up a sense of "enmity and jealousy and anger."
"The president's campaign is all about division and attack and hatred," Mitt Romney told CBS. "My campaign is about getting America back to work and creating greater unity in this country," Romney told CBS News.
"The president seems to be running just to hang onto power — I think he'll do anything in his power to try to get reelected," he said.
Obama aides responded to the outburst, apparently a bid to dent the president's high character ratings, by affecting bemusement, and pointing out that Romney won the Republican nomination partly through a negative ad onslaught.
"Hope it's not hateful to say that Mitt's budget math doesn't add up," said Obama senior advisor David Axelrod on Twitter.
Obama was wrapping up a three-day bus tour of Iowa, the midwestern swing state where he laid the foundations of his 2008 election victory, boosted by the political firepower of his popular wife Michelle.
The president was planning to target Romney on the Medicare health care system for seniors, picking at divides between his rival and his Republican running mate Paul Ryan who backs a voucher plan to replace aspects of the programme.
Obama spokeswoman Jen Psaki said the president would argue his reforms had strengthened the system by cutting wasteful spending but not benefits.
"He will lay out the choice between his plan and the Romney-Ryan plan to end Medicare as we know it, leaving new retirees with nothing but a voucher in place of the guaranteed benefits they rely on today."
"This kind of plan forces people with Medicare to pay an extra $6,400, all so Mitt Romney and Paul Ryan can give tax cuts to millionaires and billionaires."
The row over Medicare, a popular federal government programme, could be pivotal in electoral battlegrounds with substantial populations of retirees, including Florida, the largest US swing state.
The exchanges came a day after the most charged jousting in the campaign so far, with Romney telling Obama to take his "hate" back home to Chicago, after Vice President Joe Biden warned Republicans would put Americans "in chains."
"I think comments of this nature sink the White House just a little lower," Romney said, calling the remark an "unfounded charge."
"The comments of the vice president as I heard them ... were one more example of a divisive effort to keep from talking about the real issues."
The Obama campaign responded to Romney's outburst by implicitly questioning whether the Republican's temperament was suited for the Oval Office.
"Governor Romney's comments ... seemed unhinged and particularly strange coming at a time when he's pouring tens of millions of dollars into negative ads that are demonstrably false," Obama spokesman Ben LaBolt said Tuesday.
Most political experts believe the race to the November 6 election remains close, with Obama perhaps slightly in the lead and well positioned in the dozen or so battleground states that will decide whether he gets a second term.
Obama argues that Romney, a former multi-millionaire venture capitalist, would further enrich his wealthy friends with tax cuts — and put the burden on a middle class struggling to cope in a slow economic recovery.
Romney paints Obama as out of ideas, an enemy of job-creating small businesses and bent on a big government takeover of many aspects of American life, and questions whether he really understands his home country.
Romney's stellar fundraising operation has outpaced the president's in recent months, piling up over 100 million dollars in July for instance. But in one metric of the race — leveraging the Internet — Obama is still up.
The Pew Research Center said that while Romney's team averaged one tweet per day, Obama averaged 29 tweets — 17 on BarackObama (the Twitter account associated with his presidency) and 12 on Obama2012 a campaign account.
"Obama holds a distinct advantage over Romney in the way his campaign is using digital technology to communicate directly with voters," said a statement from the Pew's Project for Excellence in Journalism.