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After a disappointing second-place showing behind Newt Gingrich in the South Carolina Republican presidential primary, Mitt Romney said Sunday that he will release his 2010 tax returns this week so that he can put behind him an issue that he acknowledged is causing a big distraction for his campaign.

"I'm going to make it very clear to you right now, Chris, that I will release my tax returns for 2010, which is the last returns that were complete. I will do that on Tuesday of this week. I will also release at the same time an estimate for 2011 tax returns," Romney told "Fox News Sunday" host Chris Wallace

As Romney, Gingrich, Rick Santorum and Ron Paul move on from South Carolina to compete in Florida, whose GOP primary is Jan. 31, and Nevada after that, on Feb. 4, the former Massachusetts governor admitted "it was not a great week for me."

Distracted by the tax return question and the Iowa GOP certifying Santorum as the winner rather than Romney, who was originally declared the victor in the first-in-the-nation caucuses, Romney said he plans to look more closely at the question of Gingrich's ability to be a leader.

"I don't think that the people of this country are going to choose as the next president of the United States a person who spent 40 years in Washington as a congressman and a lobbyist," he said.

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But first, Romney has to get past the question of his taxes, which appear less an issue of whether he has filed anything wrong and more about whether his wealth can be used against him.

"If there are things in there that can be used against him we ought to know about them before the nomination," Gingrich said Sunday after hearing Romney's decision.

Gingrich, who released his own returns on Thursday, said he was satisfied with Romney's agreement to release 2010 and 2011 estimates, and said the issue comes back to whether Romney is in a position to beat President Obama.

"Do you want the establishment candidate, Governor Romney?" Gingrich asked on NBC's "Meet the Press. "I think you can draw a very strong case that in the end the dynamics of a Gingrich/Obama fight are much better for Republicans than the dynamics of a Romney/Obama fight."

Tormented by Democrats and Republicans, particularly Gingrich, who insisted on knowing about the sources of Romney's massive wealth and his holdings in offshore accounts, Romney revealed last week he pays an effective tax rate of about 15 percent.

Though lower than the 35 percent income tax rate of high-earning Americans, it is in line with his primarily receiving most of his earnings not through wages, but through investments taxed at the 15 percent rate.

According to the financial disclosure released by Romney, during 2010 and the first nine months of 2011, his family had at least $9.6 million in income. In addition, Romney investments -- worth between $7 million and $32 million -- are being held in offshore-based holdings. Such offshore accounts also can enable wealthy investors to defer paying U.S. taxes on some assets, according to tax experts, but Romney said that he's not done anything that can be used against him.

"The taxes paid on that are full U.S. taxes," he said. "I know people will try and find something. But we pay full fair taxes, and you'll see it is a substantial amount."

Romney originally promised to release the returns in April, "when they've been released by other candidates in the past," but he said given all the attention on them last week ahead of the Palmetto State primary, he wants to release them so people can "take a good look" at them.

"We'll put them on the website and you can go through the pages," he said.

"People can look through them. It'll provide, I think, plenty of information for people to understand that the sources of my income are exactly as described in the financial disclosure statements that we put out several months ago," he said.

Calling it a "mistake" to hold off as long as he did, Romney said he hopes the release will end the distraction so he can "get back to the real issues of the campaign -- leadership, character, a vision for America, jobs for America and how to rein in the excessive scale of the federal government."

While Romney tries to tack back toward the leadership race, the other candidates are also looking at Florida strategy now. Santorum scoffed at the suggestion he might leave the race so conservatives could rally behind Gingrich against Romney.

"The idea that conservatives have to coalesce in order to beat Mitt Romney, well, that's just not true anymore. Conservatives actually can have a choice. We don't have to rush to judgment,' he said.

"The longer this campaign goes on, the better it is for conservatives, the better it is for our party," Santorum told ABC's "This Week."

Paul is not really competing in Florida so that he can focus on the Nevada caucuses, a process which heavily favors Paul's grassroots approach.