Wyoming legislators on Tuesday failed to advance a bill barring so-called crossover voting in state primaries, a measure former President Trump backed as he pushes voters to oust one of his most vocal Republican critics, Rep. Liz Cheney (Wyo.).

The bill would have prohibited voters from changing their party registration on primary Election Day, barring last-minute changes that would allow them to choose the party primary in which they wanted to participate.

Supporters of the bill said making the change would prevent Democrats or independent voters from casting a ballot in the Republican primary — presumably, voters who would be more likely to favor Cheney, who voted to impeach Trump and who sits on the House panel investigating the Jan. 6, 2021, insurrection at the U.S. Capitol, over Harriet Hageman (R), Trump’s chosen challenger.

Trump publicly endorsed the bill last month.

“This critically important bill ensures that the voters in each party will separately choose their nominees for the General Election, which is how it should be!” Trump said in a February statement.

The bill passed the state Senate last month, but it ran into a headwind in the state House, where the Appropriations Committee voted Monday to recommend against its passage. The bill did not pass a deadline on Tuesday to be considered by the entire House, all but ending its chances of winning approval this year.

The proposed ban on crossover voting predates Trump’s feud with Cheney. Conservative Republicans alleged in 2018 that Mark Gordon, then the state treasurer, won the gubernatorial primary that year over conservative businessman and major donor Foster Friess with the help of Democratic voters.

Friess had earned Trump’s endorsement. Gordon, who had support from former Sen. Alan Simpson, the Wyoming Republican legend, won the primary with a third of the vote, about 9,000 votes ahead of Friess.

A subsequent data analysis from Brian Harnisch, a University of Wyoming political scientist and pollster, found just a few hundred registered Democrats changed parties in the months ahead of that year’s primary, far fewer than Gordon’s margin of victory.

About 10,000 voters in all switched affiliations to vote in the GOP primary that year, according to data from the secretary of state’s office, though it is unclear how many of those switchers actually voted in the primary or whether they backed Gordon, Friess or any other candidate.

The bill’s death will allow voters who are not affiliated with the GOP on Election Day to change their registration and cast a ballot in the Republican primary — which, in a state as deep red as Wyoming, amounts to the only game in town. No Democrats filed to run for Cheney’s seat.

Cheney told The New York Times last month she will not organize a “Democrats for Cheney” group or encourage voters to switch their party registration.

Cheney has far outraised Hageman, with help from Republicans such as former President George W. Bush and former House Speakers John Boehner (Ohio) and Paul Ryan (Wis.). Hageman joined Sen. Rand Paul (R-Ky.), a frequent Cheney opponent, at a town hall meeting Monday in Cheyenne, Wyo.