House and Senate members staring down difficult reelection races less than one year away face a tough decision as opposition to two Internet anti-piracy bills continues to mount.

The two bills — the Stop Online Piracy Act (SOPA) in the House and the Protect IP Act in the Senate — were championed by the entertainment industry as measures to prevent foreign websites from promoting copyright infringement with impunity. But a recent backlash from free-speech advocates, Internet giants and even President Obama has lowered the probability that Congress will enact them as drafted.

Both bills have roughly an even number of Republicans and Democrats signed on as co-sponsors, making it difficult for members to apply to this hot-button issue their usual calculus about where they want to position themselves on the ideological spectrum.

Sen. Marco RubioMarco Antonio RubioRubio: McCabe 'should've been allowed to finish through the weekend' For Tillerson, bucking Trump became a job-killer At least six dead after pedestrian bridge collapses on cars in Florida MORE (R-Fla.) on Wednesday withdrew his co-sponsorship in the Senate, while Republican Reps. Lee Terry (Neb.) and Ben Quayle (Ariz.) have backed away in the House. Sen. Jerry MoranGerald (Jerry) MoranSenate Commerce presses Facebook, Cambridge Analytic for answers on data Key Republicans back VA secretary as talk of firing escalates Overnight Finance: Senate passes bill to rollback Dodd-Frank | Trump names Kudlow to replace Cohn | Former Equifax exec charged with insider trading MORE (R-Kan.) signed on in June but pulled his name days later.

Sen. Orrin HatchOrrin Grant HatchSenate GOP: Legislation to protect Mueller not needed Week ahead: Lawmakers scramble to avoid another shutdown Lighthizer set to testify before Senate Finance on trade next week MORE (R-Utah), who faces a serious primary threat, yanked his support for the Senate bill on Wednesday, calling it “not ready for prime time.”

“Rushing something with such potential for far-reaching consequences is something I cannot support, and that’s why I will not only vote against moving the bill forward next week but also remove my co-sponsorship of the bill,” Hatch said in a statement. He also sent a letter to Senate Majority Leader Harry ReidHarry Mason ReidTrump presses GOP to change Senate rules Only thing Defense’s UFO probe proves is power of political favors Nevada Democrat accused of sexual harassment reconsiders retirement: report MORE (D-Nev.) last week suggesting he put off a scheduled vote on Tuesday.

In each of the two chambers, there are about a dozen members who are still on board with the bills but whose less-than-certain reelection prospects have raised the possibility that they could retreat from the legislation before further damage is done.

Sen. Scott Brown (R-Mass.), embroiled in the most closely watched Senate race in the country, has already said he will vote against the bill.

But Sen. Sherrod BrownSherrod Campbell BrownDemocratic senator: People don’t know what’s going on between Trump and Putin Power struggle threatens to sink bank legislation Pension committee must deliver on retirement promise MORE (D-Ohio) has signed on as a co-sponsor — he faces a difficult reelection fight against Ohio state Treasurer Josh Mandel (R) in November.

Other vulnerable Democrats up for reelection in 2012 who have backed the Senate bill include Sens. Bill NelsonClarence (Bill) William NelsonJuan Williams: Students change the tide on guns Republicans insist tax law will help in midterms Trump gives jolt to push for military ‘space force’ MORE (Fla.)and Bob CaseyRobert (Bob) Patrick CaseyHouse GOP frets over Pennsylvania race Do the numbers add up for Democrat Conor Lamb in Pennsylvania? Poll: Five Senate Dems would lose to GOP challenger if elections held today MORE Jr. (Pa.). 

Even non-incumbent candidates who won’t have to vote on the measures were pulled into the fray, including businessman John Brunner, the front-running Republican aiming to take on Sen. Claire McCaskillClaire Conner McCaskillGOP Senate candidate slams McCaskill over Clinton ties Dems meddle against Illinois governor ahead of GOP primary Republicans insist tax law will help in midterms MORE (D-Mo.) in November.

“As a United States senator, I will oppose all efforts to dismantle a free and open Internet,” Brunner said in a statement.

Top Democratic leaders who are not up for reelection — including Sens. Charles SchumerCharles (Chuck) Ellis SchumerConscience protections for health-care providers should be standard Pension committee must deliver on retirement promise Dem super PAC launches ad defending Donnelly on taxes MORE (N.Y.) and Dick DurbinRichard (Dick) Joseph DurbinTrump vows tougher borders to fight opioid epidemic Clinton: 'I meant no disrespect' with Trump voter comments Lawmakers rally to defend Mueller after McCabe exit MORE (Ill.) — are also on board.

In the House, the chairman of the Democratic Caucus, Rep. John Larson (Conn.), and the chairwoman of the Democratic National Committee, Rep. Debbie Wasserman Schultz (Fla.), are both on board. So is Rep. John BarrowJohn Jenkins BarrowOur democracy can’t afford to cut legal aid services from the budget Dem files Ethics complaint on Benghazi panel Barrow thanks staff in farewell speech MORE (D-Ga.), whose district was made much more difficult for him by redistricting. Rep. Bill Owens (D-N.Y.), who won his 2010 reelection by less than two points, is also a co-sponsor.

California Reps. Brad Sherman and Howard Berman have both added their names to the House bill. The two Democrats, who have a similar voting record, were pitted against each other in redistricting, and will need to find areas where they can draw contrasts ahead of a primary contest that will determine who will have a chance to keep his seat in the House.

— This story was updated at 8:44 p.m.