(San Angelo, Texas) The mayor of this West Texas sheep ranching town offered a stunning explanation when he suddenly resigned: He was in love with a man who was an illegal immigrant and had gone to Mexico.

“It wasn’t a decision that any U.S. citizen should have to make,” former Mayor J.W. Lown said in an interview from Mexico. “I left a home. I left a ranch. I left a promising political career.”

His local prominence and his run for the border on the day he was supposed to be sworn in for a fourth term caused jaws to drop, but it also became a high-profile example of the thousands of Americans who face a similar choice – separate or move abroad – because they can’t secure green cards for their partners like heterosexual spouses can.

An estimated 36,000 Americans are in this situation, said U.S. Rep. Jerrold Nadler, D-NY, citing information from the advocacy group Immigration Equality.

Bills have been introduced in Congress to treat same-sex partners like heterosexual spouses for the purposes of immigration but are likely to face a strong fight, both from gay marriage opponents and anti-immigration groups. The 1996 Defense of Marriage Act prevents immigration officials from recognizing gay marriages, even from states where they are now legal.

Proponents see the issue as a basic rights question, and Steve Ralls, a spokesman for Immigration Equality, said he believes the best chance for the legislation is as part of a larger immigration bill.

But other immigration advocates want to keep the issues separate, fearful of bogging down an already tough fight. Kevin Appleby, migration policy director for U.S. Conference of Catholic Bishops, said the push for same-sex partners in immigration is about getting recognition in federal law for gay marriage – which he opposes.

“It’s an unholy marriage of the immigration debate and the same-sex marriage debate,” he said. “It’s very combustible.”

Lown’s decision last month brought the issue to an unlikely place, a town of 90,000 where ranchers and roughnecks from the vast open lands come to do their banking and send their kids to the regional state college. The town’s only other recent brush with national fame came last year when it housed the hundreds of children taken from a polygamist sect’s ranch in nearby Eldorado.

Before his May 19 resignation, Lown (pronounced “lawn”) was considered a political rising star. The 32-year-old Republican, first elected at age 26, won his fourth term with about 89 percent of the vote.

During his tenure, Lown transformed the $600-a-year, part-time job from a mostly ceremonial position to a hands-on office. He actively appeared at thousands of community functions and went to Washington to lobby for the West Texas town – spending his own money after a few residents complained about taxpayers footing the bill.

“That’s devotion and dedication,” Councilwoman Charlotte Farmer said. “He would have gone far in the political arena in the state of Texas and perhaps farther.”

Lown’s sexuality never really came up. Some people didn’t know. Lown’s godfather, Mario Castillo, said most who knew didn’t care.

“San Angelo has a live-and-let-live attitude. As long as you don’t go around waving your boxer shorts in Sunday school, people leave it alone,” said Castillo, a longtime resident who is now a Washington lobbyist.

But Lown, who worked as a real estate agent, said his prominence meant his two-month-old relationship would be scrutinized and his 20-year-old partner might be subject to deportation.

“My heart was torn, and I had to make a decision,” he said in a conference call with local reporters shortly after his resignation.

Lown has declined to identify his partner but said the man came across the Rio Grande as a teenager and attended high school and college in San Angelo. They went to Mexico – Lown won’t say exactly where – so that his partner can apply for legal residency in the United States, generally a lengthy process for Mexicans without a U.S. citizen spouse, child or parent.

“I did not want to consciously violate the law,” Lown said. “We want to make a life together and do it in the right way and follow the law.”

Lown, whose mother was Mexican, holds dual citizenship allowing him to live legally in Mexico, he said.

San Angelo, meanwhile, will be without a mayor until the City Council decides whether to appoint someone or schedule a special election.

Lown hopes to eventually return here with his partner.

“I don’t know how long this is going to take. It could take months. It could take years, but I’m prepared to wait as long as it takes,” he said. “I hope I’ll have some shred of my good name left when this is resolved.”