Two activist groups, one liberal and one conservative, have joined together in a campaign to defeat U.S. lawmakers supporting two controversial copyright enforcement bills, the Stop Online Piracy Act and the Protect IP Act.The campaign, launched about 9 p.m. EST Tuesday, had collected more than 37,000 signatures as of 10:15 a.m. Wednesday. The activist groups, the left-leaning Demand Progress and the right-leaning Don't Censor the Net, ask supporters to pledge to work against any candidates that support SOPA or PIPA during the 2012 elections."In 2012, I will only support candidates who stand for Internet freedom and who oppose the PROTECT IP Act and SOPA," says the pledge on the VotefortheNet.com site. "I will work against any candidate, of any party, who votes to censor and stifle the Internet."Representatives of several lawmakers who support SOPA or PIPA didn't return messages seeking comments on the campaign. A spokeswoman for Senator Patrick Leahy, a Vermont Democrat and lead sponsor of PIPA, declined to comment, and spokeswomen for Representative Lamar Smith, a Texas Republican and lead sponsor of SOPA, did not return a message.VotefortheNet.com asks supporters to donate to four senators who have threatened to filibuster PIPA. Those four are Democrats Ron Wyden of Oregon and Maria Cantwell of Washington and Republicans Rand Paul of Kentucky and Jerry Moran of Kansas."When it wasn't popular, these senators led the fight against the Internet Blacklist," the site says. "Regardless of party, we need to show legislators who take on the courageous fight for Internet freedom that we have their back."Asked if he could support lawmakers he otherwise disagreed with but opposed the two bills, Demand Progress executive director David Segal said the issue is important."We're trying to make it clear to elected officials that this is an issue that many voters care about as much as any other -- or even more, as a free Internet is for many people the only thing that gives them hope that we still live in an approximately democratic society," he said.Segal is a former Democratic state representative and candidate for Congress from Rhode Island. Don't Censor the Net is run by Patrick Ruffini, former webmaster for President George W. Bush's re-election campaign and a former new media director for the Republican National Committee.Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's e-mail address is email@example.com.