While Romney's changes to Medicare would affect future retirees, the study also said that Romney's plan to get rid of Obama's health care law could raise health care costs in retirement by $11,000 for the average person who is 65 years old today by reinstating limits on prescription drug coverage.
The study was conducted by David Cutler, a Harvard professor and health policy expert who served in the Clinton administration and was Obama's top health care adviser during the 2008 presidential campaign. Cutler conducted the study for the liberal Center for American Progress Action Fund.
A senior administration official said Obama drew attention to the study as part of an overarching economic message as he takes his two-day Florida bus tour to Melbourne and West Palm Beach on Florida's Atlantic Coast.
Romney would seek to contain Medicare costs by giving retirees voucher-like government payments that they could use to either buy regular Medicare or private health insurance. But Cutler says older Americans would have to pay more out of pocket to cover the rising costs of health care.
Obama aides say they have successfully forced Romney to temporarily drop his emphasis on the sluggish economy last month by raising the Medicare issue in the wake of Romney's selection of Rep. Paul Ryan as his running mate. Romney and Ryan countered by arguing that Obama planned to cut hundreds of billions of dollars in Medicare spending over 10 years to pay for his health care plan.
Whether either side gained politically from that debate is unclear. But Republican analysts say it did take Romney off his economic focus, which they say is essential for him to win the election, especially after a bleak jobs report that showed meager job growth and more unemployed people choosing not to seek work.
Campaigning in Kissimmee, Fla., on Saturday, Obama had already worked Medicare into rally speeches.
"I want you to know I will never turn Medicare into a voucher," he told a high energy crowd of 3,000 at the Kissimmee Civic Center. "I believe no American should ever have to spend their golden years at the mercy of insurance companies. After a lifetime of labor, you should retire with dignity and respect."
Vice President Joe Biden, campaigning in Ohio, called the GOP plan "Vouchercare."
Biden said the Romney and Ryan plan would force "Mom" to go out into the insurance market and look for the best deal she can find. If the plan costs more than the voucher amount, "They say, 'Mom go borrow somewhere' " to pay for it, Biden said.
Cutler's Democratic affiliations make him vulnerable to accusations of partisanship. But much of his data is drawn from studies by the independent Congressional Budget Office, which has projected even higher costs to future retirees under a 2011 budget plan written by Ryan, a Wisconsin Republican who chairs the House Budget Committee.