Propelled by a torrent of blistering television advertisements, President Obama is successfully invoking Mitt Romney's career at Bain Capital to raise questions about his commitment to the middle class, strategists in both parties say, as the candidates engage in a critical summer duel to set the terms for this fall.
Despite doubts among some Democrats about the wisdom of attacking Mr. Romney's business career, Obama commercials painting him as a ruthless executive who pursued profits at the expense of jobs are starting to make an impact on some undecided voters, according to strategists from both sides, who differ on whether they are causing any substantial damage.
While the sense of worry and alarm that has hung over the White House for weeks is dissipating,and with his supporters relieved by the Supreme Court decision on Thursday to uphold most of his health care law, Mr. Obama faces new challenges before the conventions at the end of the summer.
People close to the Romney campaign say it could close its June fund-raising books having collected an additional $100 million, possibly more, a tally that would exceed all expectations and further extend the overall Republican financial advantage in the race.
With that cash influx, Mr. Romney's team is preparing a new advertising campaign that will aggressively portray Mr. Obama as a craven political figure, rather than the transformative leader he pledged he would be.
They began that effort in the past several days with a new ad that uses video of Hillary Rodham Clinton lashing out at Mr. Obama in the 2008 Democratic primary campaign as spending "millions of dollars perpetuating falsehoods." Aides said they were considering more ads with Mrs. Clinton or her husband criticizing Mr. Obama.
"He's just another politician," Matt Rhoades, the campaign manager for Mr. Romney, said in an interview. "He's not the Barack Obama of the last campaign."
And Mr. Obama's aides acknowledged that whatever they do, they still must contend with a troubled economy, with monthly reminders in the unemployment and job creation reports, the next of which comes out on Friday.
Mr. Romney's aides said in interviews that their strategy depended on keeping their candidate close to Mr. Obama in the polls until at least the Republican convention at the end of August. They hope to begin to pull away then with a relentless case that Mr. Obama has not been up to the job of fixing the economy - and that Mr. Romney has the experience and the knowledge to lead the nation to recovery.
They have studiously avoided getting drawn into what they have called side issues. And at times they have limited Mr. Romney's media appearances, even after the health care decision, which conservatives believe will help motivate voters who now see electing Mr. Romney as the only chance of undoing the law.
But Mr. Romney's strategy of avoiding clashes on issues other than the economy and minimizing his risks - he has no public events scheduled until at least the Fourth of July - is starting to draw criticism even from some fellow Republicans, who are urging him to take more specific stands and set out a more positive agenda.
Mr. Obama, by contrast, has put other big issues in front of the nation on his terms, most notably same-sex marriage and illegal immigration, displaying the advantages of incumbency, energizing crucial voting groups and moving public attention at least temporarily away from jobs.
But even as they have tried to expand the playing field of issues, Mr. Obama's aides said they would not let up on their efforts to challenge the core of Mr. Romney's campaign, his claim to be a better economic manager.
"We've got to make sure people fully appreciate Mitt Romney is not some safe alternative," said David Plouffe, a senior adviser to the president.
To drive home that point over the past few weeks, Mr. Obama has gone on an advertising binge, spending more than $12 million during a single week in mid-June, according to a Republican group that monitors advertising spending.
According to the independent media tracking firm CMAG, between early April and late June Mr. Obama spent at least $40 million and Mr. Romney at least $10 million, with outside groups like Crossroads GPS and Restore Our Future making up the difference for him.
The latest advertisement against Mr. Romney has been criticized by independent fact-checkers as incorrectly calling Mr. Romney a corporate raider and unfairly alleging that he "shipped jobs to China and Mexico."
Mr. Obama's acute focus on Bain has drawn complaints from Democrats, including high-profile surrogates like Mayor Cory A. Booker of Newark, who said in May that he found the attacks nauseating. And even as the liberal "super PAC" Priorities USA Action joined the attack with similar ads, some Democrats said they had concluded that the attacks were not working anyway.
But recent Quinnipiac University polls found that there were slight shifts in Mr. Obama's favor in Ohio on the question of who would do a better job handling the economy, and that he was roughly even with Mr. Romney on the question in Pennsylvania.
In the most recent NBC News/Wall Street Journal poll, 33 percent of respondents in swing states said that hearing or reading about Mr. Romney's business record had made them view him more negatively, as opposed to 18 percent who said it made them view him more favorably.
And strategists with both parties said independent voters speaking in focus groups had indicated that they had seen the ads or heard their charges and that they had raised questions in their minds about Mr. Romney's experience.
Steve Schmidt, a Republican strategist who ran Senator John McCain's presidential campaign in 2008, said the attacks on Mr. Romney's business experience appear to have resulted in a "fairly mild increase in disapproval ratings." But, he said, "it's not a huge rise over the course of a month."
And officials with Mr. Romney's campaign said that whatever questions the advertisements might have raised, they had not shifted opinions away from a general belief among swing voters that Mr. Romney is "the guy to fix the economy" and that he "will actually get the job done," said Neil Newhouse, Mr. Romney's pollster.
More important, they said, Mr. Romney remains in a statistical tie with Mr. Obama at a time when he is still recovering from his rough primary fight and is scrambling to raise money.
"As you start to put together a general election campaign, it's when an incumbent president should be at his strongest," said Stuart Stevens, a senior Romney strategist. "They've been preparing for this moment for three and a half years, and we've been in a primary until very recently."
Even with the political terrain newly settled by the Supreme Court's decision, neither side expects the campaign to move beyond its dogfight status before the party conventions and the debates.
"It's going to be very close," Mr. Plouffe said in an interview. "We're not looking for - and don't expect - seismic movement."
