The debate over whether same-sex couples should be included in the immigration overhaul is resurfacing, threatening to break the fragile coalition supporting it.

Rep. Luis Gutierrez (D-Ill.) is holding a press conference Monday to announce that he wants to extend family immigration benefits to binational gay couples. The representative leading the charge on immigration had not included that community in his original proposal unveiled last year.

The switch marks a victory for Immigration Equality , an advocate for this issue. The group estimates that there are 40,000 same-sex couples in this country with one partner who is not a U.S. citizen.

But it could also divide immigration advocates, many of whom belong to conservative religious communities that oppose gay marriage.

As Sen. Charles Schumer (D-N.Y.) unveiled the Democrats' immigration proposal last month which includes same-sex couples, the U.S. Conference of Catholic Bishops spoke up against "extending marriage-like immigration benefits to same-sex relationships."

"This proposal threatens to undermine the opportunity to bring together the Congress and the American people around a common solution to the important challenge of immigration reform," the group said in a statement.

The gay rights issue could also alienate Evangelical leaders who could sway moderate Democrats and Republicans to support immigration.

Liberal factions in the coalition argue that the same-sex issue could do the opposite: It could win them the support of gay rights activists and lawmakers who have not traditionally seen immigration as an issue relevant to them.

They point out that the Uniting American Families Act (HR 1024 ), which includes such a provision, already has 124 cosponsors in the House.

-- Ambreen Ali, Congress.org