The series of anti-SOPA activism going on today has already claimed an early victory. Marco Rubio, the Florida Senator and Tea Party favorite, dropped his support after being a co-sponsor of the bill.

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.”

I think more than anything, Rubio and the other Senators who abandoned ship on this bill of late want Harry Reid to postpone the vote next week. They don’t want to have to take the vote and anger at least one constituency, be it the entertainment moguls or the grassroots/Internet coalition. They’d rather broker some kind of compromise to keep everyone happy. But I don’t see where that compromise can come from. The movie studios want to use the federal government to muscle out piracy, even if it means destroying the architecture of the Internet. The grassroots/Internet coalition wants no part of this bill at all, and would rather use existing enforcement statutes like the Digital Millennium Copyright Act. So where can the line get drawn?

It’s important to point out that, despite this movement away from the bills, they have not died. Reid looks determined to hold a vote in the Senate next week, and the House Judiciary Committee will resume SOPA hearings in February. Even with the DNS blocking provisions stripped out, the bills include harmful provisions that would put an undue burden on Web sites to police content and force many sites off the Internet without a hearing or trial. So that’s why you’re still seeing a blackout on thousands of sites today.

Even with Rubio’s opposition, there are still no more than 15 Senators with stated opposition to PIPA, the Senate’s version of the bill, with less than a week before the vote. So more work will need to be done to put a stake through the heart of this legislation.

UPDATE: Jonathan Weisman reports that John Cornyn now opposes the bill. So that’s 16. The key here is that the Tea Party opposes the legislation, which means we could see a rush to the exits from Republicans over the next several days.

UPDATE II: Make it 17, with Senator Mark Kirk’s opposition. I’m going to mark it down now: the cloture vote next week won’t get to 60.

UPDATE III: Roy Blunt, a former co-sponsor, now opposes PIPA. That’s 18 (Chris Bowers has 19, I’m not sure where the divergence is). Senate candidate Elizabeth Warren also comes out against SOPA and PIPA.

Elizabeth believes that illegal piracy should be punished, but she has serious concerns with SOPA and PIPA. They risk chilling the innovation, diversity, and free exchange of ideas that define the Internet and have shaped our increasingly interconnected world.

UPDATE IV: A very expansive reading of the Open Congress whip count would suggest that 35 Senators now support PIPA, with 28 opposed. But that includes leaners.