The tide is clearly turning on gay rights, with same-sex marriage being legalized in states across America and several countries all over the world. But supporting gay rights can still be a political liability in Washington. According to Politico, Sen. Patrick Leahy (D-Vt.) has said that he will introduce an amendment to the Gang of Eight's immigration reform bill that would allow gay American citizens to sponsor their foreign-born partners for green cards, just like straight couples can.

That's a big no-no for Republicans, says Marco Rubio, who has served as the Gang of Eight's public face. Rubio has repeatedly said that he is confident the bill — which includes a 13-year path to citizenship, billions for border security, and new visas for high- and low-skill workers — has a good chance of passing. (Get more details on the bill here).

Now it could all come undone over this gay-rights amendment, Rubio tells Politico:

It will virtually guarantee that it won't pass. This issue is a difficult enough issue as it is. I respect everyone's views on it. But ultimately, if that issue is injected into this bill, the bill will fail and the coalition that helped put it together will fall apart. [Politico]

Of the eight senators drafting the bill, all four Republicans said they were against including the amendment in the immigration bill. Sen. Jeff Flake put his objections bluntly to The New York Times: "There’s a reason this language wasn't included in the Gang of Eight’s bill: It's a deal-breaker for most Republicans."

In the meantime, gay rights groups are calling out the Gang of Eight's four Democratic senators for supporting gay marriage but not recognizing it in the immigration bill.

"When Democrats are falling over one another to say how they support marriage equality, why are they abandoning gay families when actual legislation is on the table?" Rachel B. Tiven, executive director of gay rights group Immigration Equality, told The New York Times.

For the most part, however, liberals are preaching patience and compromise on the issue. Doug Mataconis from Outside the Beltway asks gay rights activists to look at the big picture:

Perhaps Leahy is right and his proposal really won't imperil the bill, but it strikes me that he ought to take the warnings of Rubio and Jeff Flake, both of whom support the overall Senate plan itself, in this regard. What's more important? This one issue, or overall comprehensive immigration reform? [Outside the Beltway]

Yess, liberals should be patient, writes The American Prospect's Gabriel Arana, because "with the Supreme Court poised to strike down the Defense of Marriage Act (DOMA), which bars the federal government from recognizing same-sex marriages in the states — including for immigration purposes — the future arc of gay rights bends toward justice."

In other words, if DOMA is struck down, many same-sex couples will eventually be able to claim the same immigration-related rights as straight couples do, even without this particular provision.