Missouri Senate Democrats have lead a marathon filibuster Tuesday to block a constitutional amendment that critics said would allow businesses to refuse services for same-sex marriage ceremonies. The filibuster had lasted longer than 30 hours at one point, with at least seven Democrats speaking nonstop since Monday afternoon against the legislation Republicans said would protect religious liberties.

The constitutional amendment is part of a national trend  after the U.S. Supreme Court ruled in 2015 that gay marriage was legal. It would prevent the state from penalizing any religious organization, “on the basis that the organization believes or acts in accordance with a sincere religious belief concerning marriage between two persons of the same sex.”

One of the lawmakers, Missouri State Sen. Maria Chappelle-Nadal, said she would speak for three hours Tuesday evening, “take a break, and be fresh at 3 a.m.” The filibuster is the longest continuous effort in Missouri history.

“This is a major scarring of equality in Missouri. We are living in an environment where hatred is alive, and we as a caucus are not going to tolerate it," she said on the Senate floor, the New York Times reported.

Democratic presidential hopeful Bernie Sanders and corporate giants Dow Chemical and Monsanto were among the many notable supporters who backed the marathon filibuster on social media. 

“Standing up for our LGBTQ sisters and brothers is the duty of all elected officials,” Sanders tweeted from his presidential campaign account. “This should make us all proud.”

Agricultural giant Monsanto, whose headquarters are in St. Louis, tweeted out, “We call on other businesses and the ag community to join us in speaking out against discrimination in Missouri and around the world.”

Representatives from religious groups backed the amendment, including the Missouri Catholic Conference. The legislation offers “a reasonable accommodation that can respect the dignity of all persons, including same-sex couples and those who, because of their religious beliefs, cannot in good conscience participate in a same-sex marriage ceremony in such a direct and intimate manner,” the group said in a statement.

Business groups said they were concerned the proposed law would spark a backlash akin to what other states have faced in recent years after embracing similar measures. 

“We are concerned that some provisions of Senate Joint Resolution 39 are directly counter to our Missouri values and will have significant negative economic effects on our state,” the St. Louis Regional Chamber said in a statement Monday. “As we saw in the reaction to the signing of the Indiana Religious Freedom Restoration Act last year, laws that allow those engaged in public commerce to discriminate will hurt our economy and our image as a welcoming state."

Chappelle-Nadal, a Democrat from the St. Louis area, was also an outspoken ally for human rights during protests over the police shooting of Michael Brown, 18, in Ferguson, Missouri. She is running this year for the U.S. House to represent the 1st Congressional District of Missouri.

 “I want to do my part and just have a conversation about an issue I feel is really important to us,” Chappelle-Nadal said from the Senate floor.