JACKSONVILLE, Fla. >> The first major gay rights showdown since Houston’s rancorous vote to repeal its anti-discrimination ordinance is shaping up here in Jacksonville, the largest city in the nation whose leaders have never enacted civil rights protections for gay, lesbian, bisexual and transgender people.

Like Houston, Jacksonville is a growing Southern city where religion plays a powerful role in public life. And, as in Houston, the battle here pits a well-organized coalition of gays and business forces against energized Christian conservatives who raise issues of religious freedom and the specter of male predators in women’s bathrooms. One major difference: In Houston, voters this month rolled back an existing ordinance; in Jacksonville, for now, the issue is before elected officials.

Gay rights groups have poured tens of thousands of dollars into an aggressive effort to persuade the city council to expand its existing Human Rights Ordinance, and to elect candidates who favor doing so.

For advocates, Jacksonville is a chance to regain momentum on the path to an ultimate goal: winning sweeping legal protections for gay, lesbian, bisexual and transgender people by amending the Civil Rights Act of 1964.

For Christian conservatives, wounded from repeated losses in the courts culminating in the Supreme Court’s decision in June to make same-sex marriage legal nationwide, it is a chance to show that Houston was not an isolated victory.

Hundreds of people, many wearing bright orange stickers bearing the sunburst logo of the Jacksonville Coalition for Equality, a gay rights group, turned out this month for the first of three “community conversations” that Mayor Lenny Curry is convening on the so-called HRO. The expanded ordinance is not yet written but is expected to go before the city council early next year.

Inside a standing-room-only hall, where a five-member panel took questions from a moderator and then the audience, the ripple effects of Houston — where opponents’ rallying cry was “No Men in Women’s Bathrooms” — were clear.

“It’s a fact of life that predators attack women and children in bathrooms; it happens everywhere,” said one panelist, Roger Gannam, a lawyer and former Jacksonville resident who represents Kim Davis, the Kentucky clerk jailed for refusing to issue marriage licenses to same-sex couples. He drew jeers when he said an anti-discrimination law “will make that easier” by allowing male criminals to pose as transgender.

Currently, more than 200 cities and 17 states have ordinances barring discrimination based on sexual orientation and gender identity, with no evidence of any increase in crime, proponents say.

The push here fits into a broader agenda for the national gay rights movement, which is now focused on ending discrimination in housing, employment and public accommodations. A new group, Freedom for All Americans, is trying to change laws in the states, with the ultimate goal of winning federal protections, a strategy that worked in the fight for same-sex marriage.

“We need to create a tipping point,” Matt McTighe, the group’s executive director, said. He expects legislatures in Arizona, Florida, Georgia, Indiana, Massachusetts and Pennsylvania to consider measures next year.

“Houston was a wake-up call,” said Chad Griffin, the president of the Human Rights Campaign in Washington, a gay rights group that is paying the salaries of four organizers and three strategists, all registered as lobbyists here.

For months, they have been working out of a two-room suite in an unmarked brick building beside a highway offramp, gathering names and combing through voter registration files. Supervising them is a 30-year-old field organizer, Karl Bach, who has experience in 20 states.

In preparation for Curry’s meeting, Bach and his team made a furious round of last-minute phone calls to urge supporters to turn out — and to arrive early. The effort paid off; the panel took questions first come first served, and because coalition supporters arrived first, they asked all the questions.

An 81-year-old mother of a transgender woman stood up and asked the panel, “How can I be sure that my child — all of my children — will be safe in Jacksonville?” A 9-year-old girl stood up and told the mayor, “We are such an awesome city, we should have an HRO.” Her father asked the crowd who among it had been discriminated against in Jacksonville. A third of the people put hands up.

At one point, an opponent of the law, wearing a blue “Protect First Liberties” sticker, exploded. “This is a sham!” he exclaimed, demanding to be heard. “Rules are rules!” the crowd shouted back. Frustrated, he sat down.

If Christian conservatives are not as well organized here as they were in Houston, they soon would be, Gannam said in an interview. He helped lead the opposition that defeated a similar effort in Jacksonville in 2012, and is now working with a coalition of pastors and conservative groups, including the Florida Family Policy Council, a statewide group affiliated with Focus on the Family.

And already, others are organizing locally. Raymond Johnson, a Republican strategist who runs a ministry devoted to “biblical concepts in public policy,” has been emailing a network of pastors with fliers opposing what he calls “a Christian persecution law.” He said he expected a much better turnout at the mayor’s next forum, scheduled for Thursday, which will focus on religious freedom.

“This is spiritual warfare,” Johnson said.

The fight in Jacksonville, Florida’s most populous city, with roughly 853,000 residents, has been three years in the making. After the defeat here in 2012, the Jacksonville Coalition for Equality mobilized, with support from Equality Florida and the Human Rights Campaign, and began working aggressively to elect allies to the city council. They have also lined up support from the Chamber of Commerce and prominent business leaders.

“The business case is simple,” said Steve Halverson, the chief executive of the Haskell Co., one of the city’s largest private employers. “We are handicapped if we have a culture that is the least bit intolerant or uncomfortable for anybody.”

For now, Curry is playing it safe. A newly elected Republican who won by courting both business leaders and Christian conservatives, he campaigned by saying he saw no need to change city law. But he also says he wants to take the pulse of his citizenry; in an interview, he would not say whether he would sign an expanded ordinance if it passed.

If he were to sign, Christian conservatives here said, they would press to put the matter to a referendum. Among the most vociferous opponents is the Rev. Gene A. Youngblood, the pastor of the First Conservative Baptist Church, who drew controversy this spring when he put a sign on his marquee reading “Homosexuals Must Repent or Go to Hell.”

He complained in a brief telephone interview that the Jacksonville Council is “bought and paid for with LGBT money,” and predicted: “This city will do as Houston, Texas. This city will allow citizens to vote.”

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