Labor groups are putting pressure on Democrats to deliver on their top legislative priority this year: a pro-union bill that targets state right-to-work laws.

The legislation, known as the PRO Act, has been introduced before, only to hit a wall with Republicans in the Senate. This time around, unions want to see an all-out effort from Democrats, one that extends to the White House.

“Strengthening our freedom to organize a union by finally passing the PRO Act is labor’s No. 1 priority,” AFL-CIO President Richard Trumka told The Hill on Thursday. “The PRO Act is our litmus test.”

The first test will come next week, when the bill is likely to get a floor vote on Tuesday, according to a Democratic aide.

Of the 221 Democrats in the House, 209 are co-sponsors of the legislation. Three Republicans are even backing the measure: Reps. Brian Fitzpatrick (Pa.), Chris Smith (N.J.) and Jefferson Van Drew (N.J.).

The House passed the PRO Act in a 224-194 vote last year but it was never taken up in the GOP-controlled Senate. 

Reintroduced on Feb. 4, the bill would stiffen penalties for employers who violate workers’ rights, while strengthening protections for employees on the retaliatory end. It would also make changes to the union election process and bolster collective bargaining agreements.

The measure would also go after the kinds of right-to-work laws found in 28 states that labor groups have railed against, arguing they purposely make it harder for workers to form unions.

President Biden delivered a video message on Sunday supporting Amazon workers in Alabama, who are fighting for their right to unionize in a right-to-work state.

“As President Biden said this week, the decision to join a union is a vitally important choice, a choice that should be made by workers, not their employers. Under our current labor laws, the playing field is not level — it allows corporations to restrict the freedom of their employees to take collective action to improve their workplaces. Passing the PRO Act is not just a top priority for union members,” said Beth Allen, Communications Workers of America spokesperson.

Biden’s campaign website last year said he supported the PRO Act and would even “go beyond” it by imposing even stiffer penalties on corporations that interfere with organizing efforts.

But any efforts to enlist help from the White House will likely run into stiff competition from Biden’s other legislative priorities, namely infrastructure, gun control and immigration.

Still, unions are keeping up the pressure on the White House, in hopes Biden might be able to twist some arms. 

“Labor law reform is long overdue. Like President Biden said, people should have the freedom to form a union if they choose without intimidation and fear-mongering from the boss, who’s getting rich at their expense,” said Lee Saunders, president of the American Federation of State, County and Municipal Employees, which has more than 1 million members.

Business groups are leaning heavily on Republicans to oppose the measure, particularly in the 50-50 Senate, where Democrats would need support from at least 10 senators across the aisle to overcome a likely GOP filibuster.

But industry leaders have their eyes on a few Democrats as well. They’re hoping to secure opposition from moderate Democrats, a strategy they plan to step up when the bill is in the Senate.

More than a dozen business groups wrote to Congress this week outlining their issues with the bill, and they addressed those concerns to the bipartisan House Problem Solvers Caucus, co-chaired by Josh Gottheimer (D-N.J.), and Tom Reed (R-N.Y).

“Polarizing policy proposals, such as those that prohibit fair representation, coerce broad unionization across franchised systems and restrict independent contractor qualifications to the point that franchisees would be treated as employees, would hamper the economic recovery,” the groups wrote.

The letter included the U.S. Chamber of Commerce, the International Franchise Association, the National Restaurant Association, the National Retail Federation and the American Hotel & Lodging Association.

“The franchise business community stands ready to collaborate with you on finding policies that will better support workers and employers. We support efforts that encourage brands to share information and best practices with franchise owners on COVID-19 safety measures and employee education,” they added.

Democrats acknowledge that winning over enough Senate Republicans will be an uphill if not an impossible challenge.

Rep. Andy Levin (D-Mich.), a staunch labor advocate, said he is hopeful more Republicans will sign on to the House bill but is less hopeful about prospects in the Senate.

“The PRO Act is transformational legislation that would return power from corporations to working people across the country. So, I’d love to see some of the senators who are saying they are big champions and the working class like Ted Cruz join us in actually supporting worker voice and power in our economic life. But I’m not holding my breath,” he told The Hill.