The hot-button anti-piracy legislation that sparked a revolt online is starting to become a political liability for some of SOPA’s major backers. Fueled by Web activists and online fundraising tools, challengers are using the bill to tag its congressional supporters as backers of Big Government — and raise campaign cash while they’re at it.

Among the fattest targets: SOPA’s lead author, House Judiciary Committee Chairman Lamar Smith (R-Texas), and two of its most vocal co-sponsors, Reps. Bob Goodlatte (R-Va.) and Marsha Blackburn (R-Tenn.). House Budget Committee Chairman Paul Ryan (R-Wis.) has also felt the wrath of SOPA opponents.

Even GOP presidential contenders Mitt Romney and Rick Santorum were asked by voters recently to weigh in on the bill (neither gave definitive answers, though activists have interpreted Santorum’s response as more sympathetic to SOPA than Romney’s).

It’s a stretch to think SOPA will cost any of the longtime incumbents backing the bill their seats. The legislation would give government new powers to shutter websites that peddle counterfeit products and pirated copies of movies and music.

But there are signs the issue, long the domain of think tanks and intellectual property lawyers, could become a real factor in some races.

Prominent conservative blogger Erick Erickson, for one, has promised to make life miserable for any GOP lawmaker who gets behind the bill. His first target: Blackburn.

“I love Marsha Blackburn. She is a delightful lady and a solidly conservative member of Congress,” Erickson wrote on his widely read blog, Red State. But “I am pledging right now that I will do everything in my power to defeat her in her 2012 re-election bid.”

Erickson went on to implore the left and right to “unite and pledge to defeat in primaries every person named as a sponsor” of SOPA and suggested that both sides create a fund dedicated to supporting challengers running against SOPA supporters.

“Killing SOPA is that important,” Erickson wrote.

In Ryan’s case, critics pounced after the powerful congressman issued a vague statement that they interpreted as supportive of the bill. Using the social news site Reddit, they launched an online campaign— dubbed “ Operation Pull Ryan” — to unseat him.

Ryan’s Democratic opponent, Rob Zerban, seized on the uproar. After lambasting the bill during an interview on Reddit, Zerban raked in about $15,000 in campaign donations, according to campaign manager Lisa Tanner.

The uproar wasn’t lost on Ryan. On Monday, he issued a statement opposing SOPA in no uncertain terms. While the bill “attempts to address a legitimate problem,” Ryan said, it would open the door to “undue regulation, censorship and legal abuse.”

SOPA is making waves in other House races, too.

Goodlatte’s primary challenger in Virginia’s 6th District, Karen Kwiatkowski, claimed on her website that SOPA “will dramatically increase the federal government’s role in our lives.” She asked people to contribute to her campaign and “send Bob Goodlatte a message.”

Kwiatkowski, who describes herself as a “conservative constitutionalist Republican,” told POLITICO that Goodlatte’s support for the bill was “bought and paid for” by content companies that “don’t want to adapt their business models [and] don’t want to invest in protection for their material.” That includes language software company Rosetta Stone, she said, which is based in the district.

She estimated that 20 percent — or roughly $5,000 — of the donations she received in December was attributable to SOPA. Kwiatkowski has raised about $30,000 total.

An Air Force veteran that currently raises cattle in Shenandoah County with her husband, Kwiatkowski read the bill when it was first released this fall. She argues that it lacks due process and would spawn an Internet blacklist of websites.

While SOPA isn’t a lead issue for her campaign, she said it was brought to her attention by outraged campaign supporters.

“It’s wrong, and Goodlatte doesn’t get this,” she said. “To me this stinks of some sort of rich man’s welfare program — let’s shut down all the little guys and let’s control the Internet.”

The lead lawmaker behind the bill, Smith, is also facing a Republican challenger that’s blasting SOPA. Former Arizona sheriff Richard Mack plans to file to run against Smith in Texas’s 21st District as early as this week.

“This is regulating the Internet businesses that have been doing fine without the federal government being their little micromanagers,” said Mack, who aligns himself with the tea party. “People are federally regulated to death now and Lamar Smith comes up with this brainchild.”

Smith’s campaign dismissed Mack as a perennial candidate who has switched parties repeatedly and moved to Texas only eight months ago.

SOPA “targets only foreign websites primarily dedicated to illegal activity,” Mike Asmus, Smith’s campaign manager, said in a statement. He called it “good policy that protects American consumers from dangerous counterfeit goods and American businesses from having their products and profits stolen from foreign thieves.”

“Rep. Smith does not regret the possibility of having an opponent who was defeated as a Democrat, Republican and Libertarian candidate before he recently moved into the state,” Asmus added.

Goodlatte did not respond to a request for comment. But Goodlatte has called such arguments that the bill is going to threaten the Internet nonsense, saying that SOPA would protect American jobs and keep the public safe from harmful counterfeit products like knockoff pharmaceuticals.

The Web-savvy anti-SOPA movement has coalesced quickly online, tapping into social sites such as Reddit. Recently, users created a digital hit list of sorts, naming lawmakers up for reelection this year who are supportive of SOPA and its sister in the Senate, PROTECT IP.

On the comment thread, Reddit users strategize about which lawmakers they should try to unseat and how to go after them; one user even suggested applying for PAC status for the cause.

Sens. Bob Corker (R-Tenn.) and Lindsey Graham (R-S.C.), both co-sponsors of PROTECT IP, were recurring names on the thread, as was Ryan.

Blackburn’s challenger, Jack Arnold, said in a post on his campaign website that the Tennessee Republican likes to paint herself as “staunchly anti-regulation” but her support for SOPA shows that she’s actually “regulation-loving.”

Arnold, who is running as an Independent, claims Nashville-headquartered Gibson Guitars and deep-pocketed content companies influenced Blackburn to support the bill. He added that SOPA “would give unheard-of censorship power to the Department of Justice” and “remove Google, Yahoo and Bing from their positions as market leaders in Internet searches in favor of less-restricted foreign search engines.”

Blackburn balked at that criticism.

“Critics of SOPA can’t deny the undisputed fact that piracy hurts America,” she said in an emailed statement. “The same radical left-wing special interests groups that advocated for Obama’s so-called net neutrality regulations are trying to hijack conservative principles and mislead the public about SOPA.

“The fact is SOPA only applies to dedicated foreign rogue sites that are harming American consumers and creators,” she added.

This article first appeared on POLITICO Pro at 5:32 a.m. on January 10, 2012.