Two groups opposed to an Internet sales tax are touting a poll that shows members who support it could be punished by voters.
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 Enzi (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 Begich (Alaska), Kay Hagan (N.C.), Mary Landrieu (La.) and Mark Pryor (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.