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BOSTON - The Obama campaign has an offer for Mitt Romney: Release five years of tax returns and they'll promise not to pester him about the matter anymore.

The offer, made in a publicly released letter from Obama campaign manager Jim Messina, came a day after Romney revealed that he never paid less than 13 percent in taxes in the last 10 years.

"I am prepared to provide assurances on just that point: if the governor will release five years of returns, I commit in turn that we will not criticize him for not releasing more-neither in ads nor in other public communications or commentary for the rest of the campaign," Messina wrote in the letter.

Messina's would have Romney release three years of tax returns in addition to his 2010 return that has already been made public and his 2011 returns that the GOP candidate has promised to release by October.

Just before 9 a.m. this morning, Romney's campaign manager brushed aside the offer in an e-mail that was distributed to the press by the campaign.

"It is clear that President Obama wants nothing more than to talk about Governor Romney's tax returns instead of the issues that matter to voters, like putting Americans back to work, fixing the economy and reining in spending," wrote Matt Rhoades.

"If Governor Romney's tax returns are the core message of your campaign, there will be ample time for President Obama to discuss them over the next 81 days," he wrote. "In the meantime, Governor Romney will continue to lay out his plans for a stronger middle class, to save Medicare, to put work back into welfare, and help the 23 million Americans struggling to find work in the Obama economy."

Rhoades signed off with a curt "See you in Denver," a reference to the location for the first presidential debate.

Yesterday, Romney told reporters that he looked at his tax rates, following up on a promise made to ABC News to see if he ever paid less than 13.9 percent, his rate in the one year of tax returns he has so far made public. "I did go back and look at my taxes and over the past 10 years I never paid less than 13 percent," Romney said. "I think the most recent year is 13.6 or something like that."

"But every year I've paid at least 13 percent and if you add in addition the amount that goes to charity, well the number gets well above 20 percent," Romney added.

Romney has said he will only release two years of tax returns - like Sen. John McCain did during the 2008 election - out of concern that releasing more would really do nothing to appease critics who would simply keep requesting more.

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