According to The New York Times, key Senate Republicans threaten to sink the entire immigration reform initiative if it includes a provision allowing gay American citizens to bring their life partners into the country. “It’s a deal-breaker for most Republicans,” Sen. Jeff Flake (R-AZ) told the Times. In a radio interview (quoted by the Times), Sen. Marco Rubio of Florida, who is considered reform’s indispensable Republican, was blunt: “If that issue is injected into this bill, this bill will fail. It will not have the support. It will not have my support.”

Really? Republicans will deep-six the entire effort and demolish themselves with Latino voters, business interests, and young people to prevent gay people from having someone to take care of them?

Even to write those words is to wonder whether they can possibly be true. Surely Republicans know that, according to many polls, support for same-sex marriage has tipped above the majority level and is rising. Perhaps some also know that, according to a recent Huffington Post poll, partner immigration enjoys solid 7-percentage-point support. They certainly know that, from a political point of view, the perception among younger voters that a pro-Republican vote is an anti-gay vote is toxic to the GOP brand.

These days, opposition to gay equality is heavily concentrated among white evangelical Protestants, who are heavily concentrated in the Republican base. But they are increasingly isolated from the electorate as a whole. Even a solid majority of Catholics now supports gay marriage. And Republicans themselves are split down the middle on the more general question of whether “same-sex couples should have the same legal rights as heterosexual couples.”

Even among Republicans, in other words, the constituency for policies disadvantaging gay and lesbian couples is withering. And this is where Senate Republicans want to make their stand?

Back in the day, advocates of gay equality used to shake their heads ruefully over the willingness of many politicians, many Democrats as well as almost all Republicans, to throw gays under the bus for political expediency. But today’s opponents of allowing residency for gay partners fail even the expediency test. If the idea is to demonstrate that the Republican Party is hostage to a declining and increasingly isolated share of the Republican base, or to make the party seem more irrelevant and intolerant to the younger voters on whose future it depends, one could hardly imagine a better way to do it. Or a better way to improve the political prospects of liberals and Democrats.

Set aside the politics, however. From a conservative point of view—indeed, from a social conservative point of view—keeping same-sex life partners out of the country makes even less sense substantively than it does politically. It betrays rather than upholds conservative values.

People often talk about marriage as a right. Which, of course, it is, as the Supreme Court decided years ago. But it is an unusual right: one which confers not entitlement benefits or other government-granted goodies, but responsibilities. Marriage is a commitment to care for another person forever. The vows say nothing about benefits, nothing even about lifelong love. They speak of lifelong obligation: “To have and to hold from this day forward, for better, for worse, for richer, for poorer, in sickness and in health, until death do us part.”

This is a profoundly conservative promise. Two people look after each other so that the community, the government, much of the time, doesn’t have to. In exchange, the community and government recognize the pair as next of kin and give them the tools they need to do their duty.

The single most important of those tools is the right to be present. It is very difficult to be in the hospital room with your partner if you cannot be in the country with her. Trying to keep the promise to “have and to hold” across national borders is a nightmare of vulnerability and anxiety. It’s common, as a result, for gay U.S. citizens to live overseas with their foreign partners, in effective exile. I know many gay couples in that position. All gay people do. (Thank goodness, my Chinese-born husband got citizenship years ago.)

If you are the kind of social conservative who wants to discourage gay people from having stable, committed relationships—a very intolerant and inhumane and unconservative thing to want, but just supposing you do—then breaking up other people’s marriages might seem to make sense. But it will not encourage marriage, gay or straight. It will not encourage commitment. It will not encourage family values. Instead it causes gay misery, discourages personal responsibility, and increases the burden on society.

In many years of advocating gay marriage, I’ve often said there were legitimate, nonbigoted reasons to be against it. I tried to distinguish people who opposed changing marriage, per se, from people who opposed helping gays. When I was asked how to tell the difference, I said that if someone opposes domestic-partnership laws, openly gay military service, and partner immigration, you can be pretty sure that this person’s goal is to use the law to hurt gay Americans.

Gay people are now serving openly in the military, but the other two moral yardsticks still apply. Especially immigration. Even from a conservative point of view—in fact, especially from a conservative point of view—it makes no sense to distort and disrupt gay families by depriving binational couples of the tools they need to care for each other. It makes even less sense to do that while providing aspiring newcomers with the tools they need to work, providing businesses with the tools they need to hire, and providing children who grew up in America with the opportunity to live as Americans. Unless your policy goal is to distort and disrupt gay families.

Gay-rights advocates are correct to force the issue by demanding an amendment adding partner immigration to the reform bill now moving through the Senate. They are right to expect their Democratic friends, including President Obama, to support the effort and thereby to force Republicans to announce their priorities. Just how much electoral support and moral standing does the GOP want to give up to affirm its hostility to homosexuals? The results would be, let us say, clarifying.