Two groups opposed to an Internet sales tax are touting a poll that shows members who support it could be punished by voters. 

The poll conducted for the National Taxpayers Union and the R Street Institute finds 57 percent of voters oppose the plan to allow states to collect a sales tax on Internet purchases from wholesalers with no physical presence in their states. Just 35 percent approve of the idea.

That number falls even lower with Republicans: Two thirds oppose the plan, while just 27 percent support it.

The numbers could spell trouble for Sen. Mike EnziMichael (Mike) Bradley EnziGOP is addressing tax cuts and a pension bill that could help coal miners Overnight Finance: Congress sends Trump funding bill to avert shutdown | WH sees 'tentative' deal on defense spending | GOP discovers corporate tax snag | Consumer bureau fight heats up | Apple could see B windfall from tax bill Overnight Finance: Congress sends Trump bill to avert shutdown | GOP discovers corporate tax snag | CFPB leadership battle rages MORE (R-Wyo.), the leading advocate of the plan in the Senate who is facing a primary challenge from Liz Cheney (R). 

It could also become a campaign issue for red-state Democrats like Sens. Mark BegichMark Peter BegichPerez creates advisory team for DNC transition The future of the Arctic 2016’s battle for the Senate: A shifting map MORE (Alaska), Kay HaganKay Ruthven HaganPolitics is purple in North Carolina Democrats can win North Carolina just like Jimmy Carter did in 1976 North Carolina will be a big battleground state in 2020 MORE (N.C.), Mary LandrieuMary LandrieuProject Veritas at risk of losing fundraising license in New York, AG warns You want to recall John McCain? Good luck, it will be impossible CNN producer on new O'Keefe video: Voters are 'stupid,' Trump is 'crazy' MORE (La.) and Mark PryorMark Lunsford PryorMedicaid rollback looms for GOP senators in 2020 Cotton pitches anti-Democrat message to SC delegation Ex-Sen. Kay Hagan joins lobby firm MORE (Ark.).

The proposal passed the Senate earlier this year, but was dead on arrival in the GOP-controlled House.

The poll of 1,000 likely voters was conducted from Sept. 10-11 and has a margin of error of plus or minus 3.1 percentage points.