By Matt Pearce

In a legislative showdown between LGBT advocates and religious groups, Democrats in the Missouri state Senate staged a marathon filibuster Tuesday to stop a constitutional amendment that would allow businesses to refuse to provide services for same-sex marriage ceremonies.

As of late Tuesday morning, a group of about seven Democrats has spoken nonstop for 20 hours in opposition to Senate Joint Resolution No. 39, which Republicans say would protect religious liberties and which Democrats say would enshrine anti-gay discrimination in state law.

"It sends a terrible signal to the nation and to the world about the kind of place Missouri is," Sen. Scott Sifton, a Democrat who represents south St. Louis County and who told the Los Angeles Times he has filibustered for about six or seven hours.

"We're more than happy to keep going. This is a fight we're not going to back down from," Sifton said in a telephone interview.

The constitutional amendment is part of a national wave of conservative legislation that has been introduced around the country to protect religious business owners after the U.S. Supreme Court ruled in 2013 that same-sex marriage bans were unconstitutional.

The proposed amendment bars the state from penalizing or taking tax exemptions away from any "religious organization" _ including churches, corporations, schools and hospitals, and their employees _ "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."

The legislation also bars the state from penalizing religious organizations or clergy from participating or supporting same-sex marriage ceremonies, and gives the same protections to businesses opposed to same-sex marriage because of religion.

"The state shall not impose a penalty on an individual who declines either to be a participant in a marriage or wedding ceremony or to provide goods or services of expressional or artistic creation for such a marriage or ceremony or an ensuing celebration thereof, because of a sincere religious belief concerning marriage between two persons of the same sex," the bill states.

Representatives from religious groups have backed the amendment, including the Missouri Catholic Conference, which said the legislation was "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."

LGBT advocates say the amendment would override municipalities' nondiscrimination statutes. The legislation "would have reckless intended and unintended consequences," the Human Rights Campaign, a national advocacy group, said.

"If voted into law, LGBT people and their families could suddenly find themselves at risk of being denied many basic services," the Human Rights Campaign said in a statement. "Taxpayer funded foster care providers and adoption agencies could refuse to place children in need of loving homes with same-sex couples. Taxpayer funded homeless shelters could turn away LGBT couples and their families."

A somewhat similar bill in Indiana, the Religious Freedom Restoration Act, drew widespread condemnation and threats of boycotts from LGBT activists and corporations in 2015. A top Missouri business group cited Indiana's experience while expressing concerns about the proposed amendment.

"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, calling for lawmakers to remove the business-owner exemption from the bill.

"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," the chamber said.

The Missouri chapter of the American Civil Liberties Union said Tuesday that it was standing behind the Democratic senators, saying the bill would "legalize discrimination against LGBT Missourians and their children."

The bill's sponsor, Republican Sen. Bob Onder, did not immediately respond to an email and voicemail seeking comment.

The amendment, which would be placed on the ballot as soon as November if approved, was approved by a Senate committee on Feb. 25 and has not yet been voted upon by Missouri's House or Senate. Both chambers are Republican-dominated.

One of the key filibuster supporters, Sen. Maria Chappelle-Nadal, a Democrat from the St. Louis area who was a key voice during the protests in Ferguson, has spoken for about seven hours.

Chappelle-Nadal said on the Senate floor that she wanted to go home and take a shower _ and then keep the filibuster going for up to 30 hours.

"I want to do my part and just have a conversation about an issue I feel is really important to us," Chappelle-Nadal could be heard saying in a livestream from the Senate floor.

(c)2016 Los Angeles Times