A group of black lawmakers in Missouri has pledged to fight efforts by Republicans to revise state labor laws to make it more difficult for workers to prove discrimination claims.

Members of the Legislative Black Caucus say the legislation would roll back decades of civil rights advances and protect wrongdoers by limiting the amount of damages that can be claimed in cases where discrimination is proved, The Kansas City Star reports.

Language contained in the bill making its way through the House and Senate would, The Associated Press reports, require workers who file wrongful termination lawsuits to prove discrimination was a "motivating factor" -- not simply a contributing factor -- in the employer's action.

Senate Democrats also argue that the bill would give employers less incentive to prevent discrimination in the workplace.

"This legislation would be devastating to those who have been discriminated against in the workplace, and the Black Caucus is committed to fighting these bills every step of the way," said Sen. Kiki Curls, a Kansas City Democrat.

Supporters of the bill say it would simply bring state law in line with that of the federal government.

Gov. Jay Nixon vetoed a similar bill last year, and has vowed to veto the current bill.

Curls said Monday that Senate Democrats intend to block the bill "as long as it takes," even though there are only eight Democrats in the Senate and 26 Republicans.

"We realize what our numbers are over in the Senate," she said. "But some things come down to principal."