The US House of Representatives will vote on a bill on Thursday to protect US workers’ right to form and join unions that supporters are calling the “most ambitious pro-labor legislation” in decades – and which one Republican lawmaker has dismissed as “the worst bill in Congress”.

The Protecting the Right to Organize (Pro) Act has strong support from congressional Democrats and labor leaders. Republican Kevin Hern of Oklahoma, who owns 10 McDonald’s franchises and has an estimated net worth of $93m, has called the bill an attempt to “rewrite our country’s labor laws in order to strengthen the coercive power of labor unions at the expense of workers and the economy”.

Some 215 Democrats in the House currently co-sponsor the Pro Act. Three Republicans are currently co-sponsors.

“This will protect people’s rights to form unions. Those who join a union are likely to get better wages, better benefits, and work in a safer workplace,” Democratic congressman Bobby Scott, the author of the bill, told the Guardian.

The Pro Act amends the National Labor Relations Act and the Labor-Management Reporting and Disclosure Act by allowing the NLRB to assess monetary penalties against corporations for labor law violations and impose liability against corporate executives. It also grants the board the right to reinstate workers fired for retaliation while their case is pending review.

The bill also makes it illegal for corporations to force workers to attend captive audience meetings to persuade them against forming a union, forces corporations to disclose contracts with union-avoidance consultants, and requires mediation and arbitration between newly formed unions and corporations to settle disputes over first contract negotiations.

A 2018 Princeton study found unionized workers have received 10-20% higher wages than non-union workers in similar job positions over the past eight decades. Congressman Scott said studies show labor unions have also helped eliminate gender and racial pay disparities as wages are negotiated in contracts for all workers.

“The pay disparity in unions is virtually non-existent,” he said. “For those interested in eliminating pay disparities, there is virtually no disparity between men and women, and minorities and whites, in terms of wages. Everyone gets paid exactly the same.”

Union membership in the US hit a record low in 2018, with only 10.5% of American workers belonging to a labor union. Rising income inequality has been tied to a significant decline in US union membership over the past few decades. Advocates of the Pro Act are hopeful the legislation is a step forward in working to address the problems facing American workers.

“There is a crisis in our country regarding income inequality and workers’ ability to exercise their countervailing power,” said Sharon Block, the co-director of Clean Slate for Worker Power, an initiative of Harvard Law School’s Labor and Worklife Program.

“I think the Pro Act is the most ambitious pro-labor legislation we’ve seen in years, decades maybe. There is an urgency to start to fix the problem the Pro Act addresses, but it can’t be the end of the conversation of what we need to do for workers to rebuild or build countervailing power, as we see this incredible increase of corporate power, the influence of corporations, and the wealthy’s influence on our political system.”