Facing a wave of scrutiny over his lucrative career in private equity, Mitt Romney made it clear this week that he is not going to add fuel to the fire.

In an interview with MSNBC's Chuck Todd yesterday, Romney said he has no plans to release his tax returns if he is the Republican nominee. He stuck with that line on the campaign trail in New Hampshire today.

"I can tell you we follow the tax laws, and if there's an opportunity to save taxes, we like anybody else in this country will follow that opportunity," Romney said, according to the LA Times. "But we don't have any current plans to release tax returns, but never say never."

Although candidates are not legally required to release their tax returns, it has become common practice for both party's presidential nominees to do so. If Romney makes it to the general election and sticks by his decision, he would be the first post-Watergate candidate not to release his returns.

Romney's campaign team has clearly decided that the political risk of releasing the returns outweighs the potential problems of not doing so. No one knows for sure what the documents would say, but by the candidate's own admission, the bulk of Romney's retirement income from Bain has been from capital gains, which are subject to 15% tax rate.

That means that for the past 10 years, Romney has likely been paying a lower tax rate than most middle class voters. If this is the case, that information could be devastating to Romney's presidential bid.

But withholding the returns could also be problematic. So far, Romney's Republican opponents are holding their fire. But if a serious contender emerges to challenge Romney in the GOP race, the tax issue will be a tempting line of attack against the presumptive nominee.

If Romney sails through the convention as he plans, the Democrats aren't going to let this one go so easy. Within hours of Romney's comments today, the DNC had already launched a cheeky new microsite — whatmittpays.com.