By Steve Holland and Jeff Mason
CHILLICOTHE, Ohio/OSKALOOSA, Iowa (Reuters) - Vice President Joe Biden triggered outrage from Mitt Romney on Tuesday by saying the Republican would put people "in chains" if elected president as the U.S. presidential campaign took an ugly turn.
"Mr. President, take your campaign of division and anger and hate back to Chicago and let us get about rebuilding and reuniting America," Romney told a large crowd in the battleground state of Ohio.
The election campaign between Democratic President Barack Obama and Romney has been dominated by negative tactics on both sides, but still Biden's comment was jarring and one that Republicans felt brought up racial overtones.
The gaffe-prone Biden appeared to be talking about Romney's complaints about banking regulations that the Republican says are limiting credit for small businesses. Biden told a rally in Danville, Virginia, that if elected Romney would cut regulations on banks to the detriment of consumers.
"They're going to put y'all back in chains," Biden told the crowd, a comment that for some people could evoke memories of slavery in America.
When Republicans responded with outrage, Biden tried to put the statement in context in Wytheville, Virginia, saying Republican lawmakers themselves have talked about attempts to pursue limited government to "unshackle our economy."
"The last time these guys unshackled the economy, to use their term, they put the middle class in shackles. That's how we got where we are," said Biden.
The Romney campaign, eager to portray the Obama team as willing to say anything to get elected, quickly inserted a reaction to Biden into Romney's remarks in Chillicothe, making clear he blamed Obama.
"His campaign and his surrogates have made wild and reckless accusations that disgrace the office of the presidency. Another outrageous charge just came a few hours ago in Virginia. And the White House sinks a little bit lower," Romney said.
The candidates waged their verbal combat in key battleground states that will determine the outcome of the November 6 election. Obama has built a slender lead in the polls.
Obama spent the day campaigning in Iowa, a state he won in 2008 but which is now flirting with Romney. He talked up his desire to extend tax credits for wind energy manufacturers in Iowa and elsewhere. The tax credits expire at year's end.
In criticizing Romney for opposing the tax credits, Obama brought up an often-told tale about Romney, that he once put his dog in a container and strapped it to the roof of his car to go on a family vacation.
"During a speech a few months ago, Governor Romney even explained his energy policy this way: ‘You can't drive a car with a windmill on it.' That's what he said about wind power. I wonder if he actually tried that," Obama said.
Rolling through the coal fields and farmlands of Ohio, Romney vowed to step up coal production if elected to create jobs.
Ohio is a must-win state for him and he motored across the state in his campaign bus with Ohio's Republican Governor John Kasich and Senator Rob Portman, who had been on Romney's vice presidential short list.
"We have 250 years of coal. Why the heck wouldn't we use it?" Romney told coal miners wearing hard hats in Beallsville. "By the end of my second term, I make this commitment: We will have North American energy independence. We won't have to buy oil from Venezuela and the Middle East."
Romney is seeking to use the announcement of congressman Paul Ryan as his vice presidential running mate to give a spark to his campaign after he fell behind Obama in several recent voter polls.
But there are questions as to whether Ryan, a conservative budget hawk from Wisconsin, will give the campaign a significant boost.
Although the Ryan pick energized Republicans, polls show a mixed picture so far among the electorate as voters take stock of a budget proposal by Ryan filled with spending cuts that has been an easy target for Democrats.
Ryan has been slammed for proposing deep cuts to the social safety net, particularly the Medicare program for the elderly. In an interview with Fox News, Ryan made his first comments on his controversial Medicare plans.
He said Medicare in its current form is headed for bankruptcy and his proposal would save it by cutting spending by $205 billion in the next decade compared with Obama's budget plan.
The Romney campaign is facing the issue head-on, releasing an ad accusing Obama of cutting $716 billion from Medicare to pay for his healthcare overhaul.
"We're the ones who are not raiding Medicare to pay for Obamacare," Ryan told Fox when asked how he and Romney think they can gain from their stance on Medicare.
"We're the ones continuing the guarantee of Medicare for people in or near retirement. And you have to reform it for the younger generation in order to make the commitment stick for the current generation."
(Editing by Alistair Bell and Christopher Wilson)