NEW YORK (AP) - The core of his presidential candidacy under attack, Mitt Romney has yet to shape a playbook to defend a quarter-century in the business world that created great riches for himself and great hardship, at times, for some American workers.
Romney and his aides have struggled to respond consistently to intensifying criticism about his tenure at Bain Capital and how it would be reflected in his presidency. The lack of a cohesive message stems, in part, from Romney's fundamental belief that any debate that puts the economy front and center is a win for Republicans. Public polling shows most Americans are not satisfied with the pace of the recovery under Obama's watch.
The election, Romney aides say, will be a referendum on Obama's economic leadership far more than a question of Romney's business career, regardless of how much Democrats highlight that issue.
So far, Romney aides have let Democrats - led by President Barack Obama - do most of the talking.
Obama sharply attacked Romney's background as a venture capitalist on Monday, offering his most expansive comments to date about how Romney's role as founder of the Boston-based private equity firm doesn't necessarily translate to the White House.
"If your main argument for how to grow the economy is 'I knew how to make a lot of money for investors,' then you're missing what this job is about," Obama said during a news conference at an international summit in Chicago. "It doesn't mean you weren't good at private equity, but that's not what my job is as president. My job is to take into account everybody, not just some. My job is to make sure that the country is growing not just now, but 10 years from now and 20 years from now."
He added: "This is not a distraction. This is what this campaign is going to be about - is what is a strategy for us to move this country forward in a way where everybody can succeed?"
Romney did not respond personally to the broadside. Instead, his campaign issued a written statement as he courted donors on Wall Street in the midst of a three-day fundraising tour. In the statement, Romney said Obama was once again attacking the free enterprise system.
"What this election is about is the 23 million Americans who are still struggling to find work and the millions who have lost their homes and have fallen into poverty," he said. "President Obama refuses to accept moral responsibility for his failed policies. My campaign is offering a positive agenda to help America get back to work."
The Romney campaign has offered several defenses since Obama's re-election team launched an all-out assault against Bain: It's a simple distraction, an affront to free markets, an attempt to divide the nation, a misreading of the firm's success. The Romney campaign released a Web video last week featuring workers from an Indiana company that benefited from Bain's involvement.
However, Romney himself has generally avoided the issue as he spends most of his time privately raising money. He ignored Obama's criticism during a $2,500-a-plate reception at the Waldorf-Astoria hotel.
"I understand the economy because I've lived in it," he said. "And by the way, I've been successful, but I've also lost. There's sometimes I failed. I probably learned more from failures than from the successes. But I know how this economy works."
Romney's relative silence was made possible, in part, by a gaffe by Newark, N.J., Mayor Cory Booker, an Obama supporter who on Sunday called exchanges by the campaigns over Bain "nauseating" and a distraction from issues that interest voters. He walked back his comments after they dominated the campaign news for a day.
Obama is running television ads across five swing states featuring a former worker who likens the firm Romney founded to a vampire. The president's re-election campaign has also released Web videos and hosted multiple conference calls with employees from companies that suffered under Bain's leadership.
Romney senior aide Stuart Stevens described the television ad as "performance art gibberish."
"Shouting louder and getting more angry is not very persuasive," Stevens said in response to the line of attack. "The idea that people are walking around with less of a paycheck or higher gas prices because of something Bain Capital did 20 years ago is absurd."
Romney faced similar criticism from former House Speaker Newt Gingrich during the Republican primary. Gingrich accused Romney of "looting a company" and suggested that he return money earned "from bankrupting companies and laying off employees over his years at Bain."
The argument helped fuel Gingrich's surprise victory in South Carolina. Democrats are betting big that it will help Obama win over working-class voters in November, citing polling that suggests Romney would struggle with lower-income voters. But exit polling from the GOP primary shows Romney won such voters about half of the time.
In a rare recent interview on Bain, Romney told a conservative radio host last week that the closure of a Florida factory under Bain's control was not his problem. "The steel factory closed down two years after I left Bain Capital. I was no longer there. So that's hardly something which is on my watch," he said.
The Obama campaign has pointed out, however, that Romney continued to profit from Bain's investments years after he left.
Romney also opened himself to new criticism by resurrecting a controversy over the number of jobs he created at Bain. In the radio interview, he jabbed the Obama campaign for failing to mention that Bain created "over 100,000 jobs." He has struggled for months to back up the jobs claim.
Bain offered this statement Monday responding to Democratic criticism: "Despite political attacks that emphasize the few companies that have struggled, the facts are that during Bain Capital's ownership, revenues grew in 80 percent of the more than 350 companies in which we have invested."
The former Massachusetts governor co-founded Bain in the early 1980s, but he left in 1999 to run the Salt Lake City Winter Olympics and pursue a political career. He has lived off his investments and retirement package ever since.
His net worth is now as much as $250 million, which would make him among the wealthiest presidents ever elected.