WASHINGTON ― Sen. Steve Daines (R-Mont.) has a devious plot to put Democrats on the record as to whether they support a government-run, single-payer health care system.

On Wednesday, in a wily attempt to troll Democrats, the Montana Republican proposed an amendment that would expand Medicare to the entire U.S. population. The amendment is expected to receive a vote later this week while the Senate considers the GOP health care bill.

Daines, like all his GOP colleagues, doesn’t actually support a single-payer system. (Asked Wednesday whether he would vote for his own amendment, Daines smiled and shouted, “No! I don’t want single-payer!”) The amendment is not expected to pass. It will, however, offer some interesting insights on Senate Democrats.

For example, the vote will force vulnerable Democratic senators who are up for re-election in 2018 to take a position on an issue that is viewed favorably by liberals, yet much less favorably among the public as a whole.

The vote will also give Democratic senators who are considering running for president in 2020 an opportunity to align themselves with progressives, who are beginning to view single-payer as a key litmus test at the ballot box.

Sen. Bernie Sanders (I-Vt.), who popularized “Medicare for all” among progressives with his insurgent presidential campaign last year, plans to introduce legislation later this summer that would implement a single-payer system. A spokesman for Sanders told Vox that the senator planned to vote against Daines’ amendment, giving other Democrats cover to do the same

“The Democratic caucus will not participate in the Republicans’ sham process. No amendment will get a vote until we see the final legislation and know what bill we are amending,” the spokesman said.

Democratic Party leaders have resisted the idea of running on single-payer, out of concern that Republicans would use a historically unpopular policy against them. Senate Minority Leader Chuck Schumer (D-N.Y.), however, raised eyebrows earlier this month when he said that a single-payer health care system is now “on the table.”