“Gang of eight” immigration negotiators purposely didn’t include provisions for immigrants in same-sex relationships in their bipartisan bill, but the issue they so carefully avoided may rear its head this week.

As the Senate Judiciary Committee prepares for its Thursday markup of the group’s comprehensive immigration bill, it remains unclear whether Chairman Patrick J. Leahy will offer an amendment to allow same-sex partners of American citizens and permanent residents to gain legal status.

Whether Leahy decides to offer it in committee or on the floor matters because the provision has a much better shot of adoption if offered during the markup than it does during full Senate debate.

Republican “gang of eight” Sens. Jeff Flake of Arizona and Marco Rubio of Florida have told multiple media outlets that including the provision, known as the Uniting American Families Act, could be the kind of deal-breaker that would take down the bill. But Leahy dismissed that notion Sunday on “Meet the Press.”

“We’ve had about 10 different things that people say will kill it. If we don’t make the fence long enough, that kills it. If we don’t have a high enough fine, that kills it.  The fact is there are a lot of people who want to kill an immigration bill no matter what,” the Vermont Democrat said. “We will have votes on this. People can vote for or against any one of these amendments.”

Asked about the issue last week during an appearance on Hugh Hewitt’s radio show, Rubio didn’t mince words, as David M. Drucker noted on the Goppers blog. During the interview, Rubio said:

“It was not intended to cover everybody in every situation. We acknowledged from the beginning that there are people that will not be able to take advantage of the bill. It’s not a blanket bill that covers every immigration scenario. Second, this immigration bill is difficult enough as it is. There are already enough questions being asked, questions that need to be answered, legitimate points that are being raised. If you inject something like this in the bill, it will die. The coalition behind it will fall apart, and it will make it, that will not pass. It’s just that simple. If that issue is injected into this bill, this bill will fail. It will not pass, it will not have the support, it will not have my support, and so I hope we can avoid this.”

Democratic Sens. Charles E. Schumer of New York and Richard J. Durbin of Illinois would be hard-pressed to vote against the language in the Judiciary Committee, given their support for expanded gay rights and their home-state constituencies. But as members of the bipartisan group that negotiated the bill, they have an informal agreement to vote against contentious provisions that could paralyze the debate.

“If we feel the bill can be improved by various amendments, we will support those amendments,” Sen. John McCain, R-Ariz., explained April 25. “But if it’s an amendment that is designed to kill the bill, as happened in 2007, we will probably together defend the bill from going down.”

The amendment to allow gay couples with one foreign partner to gain residency or citizenship for the second partner the same way heterosexual married couples do could be the first test. On this question, it seems likely that Schumer and Durbin would side with Leahy if asked to cast a vote. Without Durbin’s and Schumer’s support, the provision would almost certainly fail in committee, and the political fallout could be potentially ugly for them.

However, if Leahy just waited until floor consideration, Durbin and Schumer might be spared the trouble. Offering the amendment on the Senate floor would require a more dramatic uphill climb, because opponents would be all but certain to require a 60-vote supermajority for adoption. So, Durbin’s and Schumer’s votes for the amendment would be unlikely to push it over the top, and its failure would ensure their underlying agreement with Republicans in the group would remain intact.

But Leahy may not be swayed to help out the duo. His contention that the language regarding gay couples wouldn’t sink the bill seems to be based in part on the past example of his Violence Against Women Act re-authorization.

That bill eventually became law, but not until after intense wrangling in the House that included debate over provisions regarding same-sex relationships and protections on tribal lands. On that House vote, 87 Republicans joined with Democrats to send the final measure to President Barack Obama’s desk. In that case, moderate Republicans in both chambers demonstrated that they would vote for expanded protections for the lesbian, gay, bisexual and transgender community.