Banking on support from community, religious and political leaders, gay rights activists here are in a close fight to prevent repeal of St. Paul's ordinance prohibiting discrimination against homosexuals.

The repeal referendum Tuesday marks the first major challenge of gay rights legislation since a group headed by entertainer Anita Bryant promoted repeal of a similar ordinanc in Miami last June. Similar referendums are scheduled May 9 in Wichita, Kan., and May 23 in Eugene, Ore.

Leaders on both sides of the St.Paul dispute predict that the vote will be close, with a large number of undecided voters determining the outcome. The St. Paul Dispatch reported Friday that its poll found 35 percent for repeal of the ordinance, 32 percent for upholding it and 33 percent undecided.

The St. Paul ordinance, which bars discrimination in housing, employment and other fields on the basis of sexual preference, has been on the books four years. But it was not until after the Miami vote that the repeal movement here got under way.

The drive to repeal is led by the Rev. Richard Angwin, 33, a Baptist minister who bills the issue as one of morality and "parents' rights."

Fighting to save the antidiscrimination ordinance is a coalition called St. Paul Citizens for Human Rights. The coalition has marshaled support from a broad base.

Yesterday, it released letters backing the ordinance from Minnesota's senators, Muriel Humphrey and Wendell Anderson, both Democrats and the Democratic congressman from St. Paul, Bruce F. Vento.

The city's Democratic mayor, George Latimer, as well as two former Democratic mayors, a former Republican mayor and five of the seven City Council members have also backed the ordinance.

Other supporters include the state central committee of the Democratic Farmer Labor Party, the school board president, various labor groups including the Teamsters, and a long list of political, civic, education and religious figures here.

"Opposition to repeal continues to grow," says Craig L. Anderson, a coalition spokeman.

Many advocates of the ordinance argue that the issue isn't the rights of homosexuals but the rights of individuals.

"We are trying to convey to the people that we are not endorsing a way of life but the human rights of individuals," says Mayor Latimer.

In her letter, Humphrey said: "I note that since this ordinance has been in effect for four years there have been no major difficulties nor have there been problems to indicate any reason why the human rights ordiance should not be continued."

But Rev. Angwin and other opponents of the ordinance claim repeal is necessary on moral grounds and for protection of children, who could learn about homosexuality as "an alternative lifestyle" from gay teachers.

Lauching his repeal drive under the banner Citizens Alert for Morality (CAM), Angwin inlisted the support of City Councilwoman Rosalie Butler, about 75 ministers or churches, the Orthodox Rabbinical Alliance of America and a number of Baptists.

Both sides held rallies last week. About 5,000 attended a prorepeal rally promoted by Angwin Wednesday. Bryant had been scheduled to appear then, but was replaced by her husband, Bob Green, after she became ill. The same night, repeal foes drew about 1,000 to rallies at the Capitol steps and about 200 to a theater near the antigay meeting.

St. Paul's ordinance is broader than the one repealed in Miami. The repeal proposal also includes a section that opponents claim could be used to allow schools run by religious denominations to exclude minorities.