House Republicans plan to introduce a bill Wednesday that would institute right-to-work policies in the entire country if it became law, delivering a severe blow to the labor movement.

Right-to-work laws give workers the option to stop supporting unions while still enjoying the benefits of representation. There’s nothing new about such proposals being made in Washington ― what’s different now is the political climate, which should alarm labor unions and their allies.

Republicans who back such laws control both chambers of Congress and the White House for the first time in years. Meanwhile, more and more states under GOP control continue to pass their own right-to-work measures, increasingly making them the norm rather than the exception.

Republicans and business groups would still face a Democratic filibuster in the Senate. But they have all the momentum on this issue, and there’s no reason to think that will change anytime soon.

A spokeswoman for Rep. Joe Wilson (R-S.C.), a sponsor of the legislation, said as much in a note to reporters Tuesday.

“Similar legislation has been introduced in the past, but we believe that this year, the legislation could garner more support than ever before,” Leacy Burke wrote.

Under U.S. labor law, a union must represent all the employees in a workplace it has unionized, even those who may not want to be in a union. Unions argue that it’s only fair for all workers to contribute money to help cover the costs of bargaining.

But right-to-work laws make such arrangements illegal, allowing workers to opt out of paying fees to a union that will have to represent them anyway. Unions call the phenomenon “free riding.” Supporters of right-to-work laws argue that no worker should be required to support a union, regardless of whether it bargains on his behalf.

Republican lawmakers and business groups have had startling success with right-to-work legislation in the last few years. Indiana, Michigan, Wisconsin, West Virginia and Kentucky have all gone right-to-work since 2012; in Kentucky, it was essentially the first order of business last month when the GOP assumed full control of the statehouse for the first time in nearly a century.

Twenty-seven states are now right-to-work, and Missouri and New Hampshire could soon follow suit. Union-dense, Democratic-leaning states on the coasts are highly unlikely to pass their own right-to-work laws, but a federal statute could take care of that for them. The passage of national a right-to-work bill would make it the law of the land in all states, regardless of their own statutes.

A Democratic filibuster is currently the only sure firewall against a federal right-to-work law. Although President Donald Trump has tried to play nice with certain unions, he voiced support for such policies while on the campaign trail.

“I love the right to work,” he said last February. “It is better for the people. You are not paying the big fees to the unions.”

Even if Democrats can beat back such proposals in Congress, right-to-work may spread anyway thanks to the Supreme Court. Unions narrowly dodged a bullet last year when the case known as Friedrichs died with a split decision following Justice Antonin Scalia’s death. A conservative majority could have ruled in favor of the plaintiffs, a group of public school teachers in California who argued that workers in public-sector unions should not be required to pay any union fees.

A ruling against unions would effectively make the entire public sector right-to-work throughout the country, regardless of state laws. Although they did not succeed with Friedrichs, right-to-work backers plan to try again once a solid conservative majority is in place on the Supreme Court.

Trump put forth a conservative nominee, Neil Gorsuch, on Tuesday.