JEFFERSON CITY - The filibuster of a bill that would change Missouri’s workplace discrimination laws ended around 1 a.m. Thursday morning, nearly 15 hours after it began.

But the senator who led the effort, Democrat Maria Chappelle-Nadal of University City, said the fight would likely continue later this session.

The bill would require workers who claim discrimination in wrongful-termination lawsuits to prove that bias was a “motivating” factor instead of a “contributing” factor, as mandated under current law.

It would also would lower the amount of punitive damages that could be awarded in an employment discrimination case and makes changes to Missouri’s whistleblower laws.

On Monday, the Legislative Black Caucus vowed to block the measure, arguing that it rolled back decades of progress on civil rights and protected wrongdoers by limiting damages that can be awarded if discrimination is proved.

To end the filibuster, Republicans agreed to an amendment striking a section of the bill critics contend would have led to most discrimination cases never making it to a jury. Parties to a discrimination case would now be able to demand a jury trial.

The bill must be approved once more before it goes to the House, which briefly debated a similar measure on Wednesday afternoon.

Chappelle-Nadal – who was joined in her effort by Democratic Sens. Kiki Curls of Kansas City and Robin Wright-Jones of St. Louis -- said the Black Caucus will continue to fight for changes in the legislation, and another filibuster could still occur.

“We’re not okay with the bill, even with the changes made today,” she said, later adding: “I’m ready and willing to stand up for another 10 hours. Fifteen hours if I have to. What I did today is, no one believed I would stand up for as long as I did. I proved them wrong.“

Democratic Gov. Jay Nixon vetoed similar legislation last year. Republicans have said passing the bill again is one of their biggest legislative priorities. They argue that since the bill makes state law mirror federal law it won’t deter any legitimate discrimination lawsuits.

"Everything in this law takes us back to the federal law that Martin Luther King Jr. applauded as it was signed," the bill’s sponsor, Republican Sen. Brad Lager of Savannah, told the Associated Press. "To insinuate anything other than that is just not factual."