Obama and other Democratic presidential candidates previously have signaled support for this idea.
But during an interview on NBC's "Meet the Press," Obama said subjecting more of a person's income to the payroll tax is the option he would push for if elected president.
He objected to benefit cuts or a higher retirement age.
"I think the best way to approach this is to adjust the cap on the payroll tax so that people like myself are paying a little bit more and people who are in need are protected," the Illinois senator said.
"That is the option that I will be pushing forward."
Currently, only the first $97,500 of a person's annual income is taxed. The amount is scheduled to rise to $102,000 next year.
'Not sufficient' to finesse the issue
Obama's proposal could include a gap or "doughnut hole" to shield middle-income earners from paying more in taxes, he said.
Obama has tried to draw contrasts between himself and front-runner Hillary Rodham Clinton on Social Security, saying on the stump and in TV ads that she has dodged tough questions about its finances.
Obama said some tough decisions will be in order because Social Security is the most important social program in the country.
"It's not sufficient for us to just finesse the issue because we're worried that, well, we might be attacked for the various options we present," he said.
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Clinton has said growing the economy will pump more money into Social Security's coffers. She also has said she would create a bipartisan commission to recommend solutions.
Social Security is projected to start spending more than it collects beginning in 2017, with its trust fund depleted in 2041.
Obama also invoked his friend, billionaire Warren Buffett, who Obama said has expressed concern that he pays less in Social Security taxes than anyone else in his office.
"And he has said, and I think a lot of us who have been fortunate are willing to pay a little bit more to make sure that a senior citizen who is struggling to deal with rising property taxes or rising heating bills, that they've got the coverage that they need," Obama said.
On the Republican side, candidate Fred Thompson unveiled a Social Security proposal last week that calls for reducing benefits to future retirees and creating voluntary personal retirement accounts. The plan is similar to one put forth by President Bush that ultimately stalled in Congress.
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