In its study, the Tax Policy Center did not score Romney's plan directly, saying it lacked sufficient details. Instead, the center said the plan represented a number of Republican proposals.
The Romney campaign officials said Thursday that the specifics of the tax proposal remain to be worked out, with deputy policy director Jonathan Burks adding that Romney, if elected, "would write a tax bill that would achieve those goals."
"It's not a question of today we have a 2,000-page tax plan," Burks said.
Tax policy has become a central economic issue, with Congress deadlocked over proposals to extend most or all of the Bush-era tax cuts set to expire at the end of the year.
Romney and Republicans want to extend all the Bush tax cuts for now to prevent any increase, while Obama says the lower rates should not continue for the wealthiest 2% of Americans to bring more fairness to the system. Both sides call for comprehensive tax reform after the election as part of necessary deficit reduction steps.
The issue touches on the foundations of the nation's political divide, with Republicans driven by their conservative base seeking to shrink government to reduce deficits while Democrats want a blend of spending cuts and more tax revenue in order to maintain what they consider essential services and entitlement programs.
With just over three months until the November election, the race has become a contentious struggle to convince voters that the other guy would take the country in the wrong direction.
In anticipation of Obama's Florida trip Thursday, the Romney campaign released a new ad in the state that blames the president for a stalling economy there.
Florida, currently rated a "toss up" on CNN's Electoral Map, has been hard hit by a weak housing market. Its unemployment rate of 8.6% is higher than the national average, but down from a high of 11.4% in 2010.
A Quinnipiac University/CBS News/New York Times poll released Wednesday showed Obama with a 51%-45% lead in Florida, which has 29 electoral votes.
Another new Romney ad Wednesday hammered Obama over unemployment and other economic problems, saying: "Americans need a change. We need a new president."
Obama's campaign responded to the ad by citing Romney's opposition to the auto industry bailout.
"Let's get this straight -- the very person who argued for the U.S. auto industry to go bankrupt, something that would have caused more than a million jobs lost and utter economic devastation in the Midwest, is now trying to attack the president on how it was handled?" campaign spokeswoman Lis Smith said in a written statement.
Meanwhile, the liberal group MoveOn.org will run a 30-second television spot in battleground states mocking the amount of money spent on Rafalca, the dressage horse competing at the London Olympics that is co-owned by Romney's wife, Ann.
The group said the ad to air in Nevada, Ohio and Pennsylvania is told from the perspective of the horse, pointing out that the Romneys spend $77,000 a year for its upkeep.
"After Mitt Romney repeals health care and ships your jobs overseas, I daresay your life won't be nearly as pampered as mine," it concludes. "After all, you're not one of his horses."
In a statement, MoveOn.org's executive director said the group was not lampooning the horse itself.
"There's nothing wrong with taking good care of a horse, but there's something messed up about a millionaire who spends twice what most Americans make in a year caring for a horse, but wants to take away people's health care and offshore their jobs," Justin Ruben wrote.