Workers Voice, the super PAC of the AFL-CIO, is supporting Senate Majority Leader Harry Reid in the fight over Mitt Romney's tax returns.

The super PAC announced plans on Monday to ramp up efforts calling on the presumptive Republican presidential nominee to release more tax returns. The largest union-affiliated super PAC, Workers Voice launched a petition where anyone can sign and back up the recent charge led by Reid. The group also plans to add the tax return issue to its protests outside of Romney campaign events.

Workers Voice is also doing an extra push to support Reid in his home state of Nevada. Las Vegas AFL-CIO executive secretary-treasurer Danny Thompson released the following statement Monday to coincide with Reid's upcoming visit to the Silver State for the Clean Energy Summit:

"Romney's secretive behavior in hiding his tax returns raises questions about if he actually did pay any taxes or if he had enough corporate loopholes to avoid paying his fair share. Our members pay their fair share every day -- Romney could learn what it really means to support your country from their leadership example. If Romney paid taxes, then let's see it. If he didn't, then he doesn't meet the leadership qualities required by our members to win Nevada in November."

Last week, Reid ignited a firestorm when he told The Huffington Post that Romney didn't pay taxes for a period of 10 years. Since then the Senate Majority Leader has stood by his claims, which he says are built on information from an anonymous Bain Capital investor. Romney responded by denying the allegations and telling Reid to "put up or shut up."

But Romney's opponents refuse to let the issue fade into the background. Robert Gibbs, campaign adviser to President Barack Obama, poked fun at the former Massachusetts governor Sunday, saying Romney could resolve the entire tax return ordeal by simply heading to Kinko’s.

"We could put this to rest tomorrow," Gibbs said on CNN’s "State of the Union." "Mitt Romney can go to Kinko's, photocopy his tax returns. There are several hundred pages. He could hand them out to people like CNN and to reporters all over the country, and we wouldn't talk about this tomorrow. We wouldn't say, 'Is he paying taxes? What's he paying?' The whole world would know what loopholes he's taking advantage of."

Also on HuffPost:

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  • Ron Paul

    "Politically, I think that would help him," Paul said in a interview with <a href="" target="_hplink">Politico</a>. "In the scheme of things politically, you know, it looks like releasing tax returns is what the people want."

  • Richard Lugar

    "I have no idea on why he has restricted the number to this point," <a href="" target="_hplink">Lugar said</a>.

  • George Will

    "I don't know why... he didn't get all of this out and tidy up some of his offshore accounts and all the rest," Will said on ABC's "<a href="" target="_hplink">This Week</a>." "He's done nothing illegal, nothing unseemly, nothing improper, but lots that's impolitic."

  • Bill Kristol

    "He should release the tax returns tomorrow. It's crazy," Kristol said on "<a href="" target="_hplink">Fox News Sunday</a>." "You gotta release six, eight, 10 years of back tax returns. Take the hit for a day or two."

  • Robert Bentley

    "I just believe in total transparency," Bentley told <a href="" target="_hplink">ABC News</a>. "In fact, I was asked today that question -- do you think that Governor Romney should release his tax returns? And I said I do. I said, I release my tax returns. I may be the only public official in Alabama that does, but I release mine every year and I just believe that people should release their tax returns. And if you get them out and just get past that, it just makes it so much easier."

  • Haley Barbour

    When asked on "<a href="" target="_hplink">The Situation Room</a>" if Romney should release more returns, Barbour said, "I would. But should it be an issue in the campaign? I don't think it amounts to diddly."

  • Michael Steele

    "If there's nothing there, there's no 'there' there, don't create a there,'" Steele said on MSNBC.

  • David Frum

    "Tax returns the next problem. Releasing returns under pressure: more weakness, more pain," Frum <a href="" target="_hplink">tweeted</a>.