WASHINGTON -- With thousands of websites large and small blacked out Wednesday in protest of the proposed Stop Online Piracy Act, a House bill, and its Senate counterpart, the Protect IP Act, another co-sponsor of the legislation has withdrawn his support -- Sen. Marco Rubio (R-Fla.).

Home to the Disney World and Universal Studios theme parks, Rubio's Florida may be the most Hollywood-centric state outside California, and Rubio had been one of the first senators to sign on in support of Protect IP when Sen. Pat Leahy (D-Vt.) introduced it this past spring. In a frank statement posted to his Facebook page on Wednesday, Rubio hinted at a Beltway truth that many other wavering Protect IP and SOPA supporters have been hesitant to admit: More than one lawmaker signed on to the legislation without understanding its technical workings and potential problems, believing it to be an uncontroversial, bipartisan bill that would support American industries.

"Earlier this year, this bill passed the Senate Judiciary Committee unanimously and without controversy," Rubio wrote. "Since then, we've heard legitimate concerns about the impact the bill could have on access to the Internet and about a potentially unreasonable expansion of the federal government's power to impact the Internet. Congress should listen and avoid rushing through a bill that could have many unintended consequences."

Rubio called for Senate Majority Leader Harry Reid (D-Nev.) to "abandon" his plans to bring Protect IP to a floor vote early next week.

Opponents of the legislation were quick to celebrate Rubio's conversion.

"With the influence of Hollywood money in the entire political system, everyone is taking a risk by coming out against these bills. But I think what we're seeing is that the tide has turned, and it's now politically safe for them to come out," said Josh Levy, the Internet campaign director for FreePress.org, a nonprofit media watchdog group whose website is blacked out today to protest the legislation.

"Grassroots activism has stripped away the vote from Disney World's senator and made California's senators much more likely to vote no," said David Segal, executive director of Demand Progress, a liberal activist group.

Segal was alluding in particular to the position of Sen. Dianne Feinstein (D-Calif.), who was once a Protect IP co-sponsor but began seeking to amend the bill in recent weeks. Feinstein sought to broker a compromise between Hollywood and Silicon Valley interests, but Bob Iger, CEO of the Walt Disney Company, declined the invitation on behalf of the major movie studios. Although she has not formally withdrawn her support for Protect IP, Feinstein is now trying to alter the legislation to allay concerns from the tech community.

Corporate film studios and major record labels laud Protect IP and SOPA as a robust effort to crack down on the piracy of American goods. But online giants, as well as tech experts and free speech advocates, have decried the bill's copyright protection strategy for threatening the normal functioning of the Internet and facilitating First Amendment violations by deploying extreme techniques similar to censorship tools used by the Chinese government.

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Disclosure: HuffPost's parent company, AOL Inc., is lobbying against SOPA and PIPA.