In recent months, one court after another — in Virginia, Oklahoma, Texas, Michigan, Tennessee, Ohio, and Kentucky — has either ruled a state ban illegal or said the state must recognize legal marriages performed in other states. It now seems all but inevitable that sooner rather than later, the Supreme Court will answer the question of whether or not a state can ban same-sex marriage.

Yesterday was another bad day in court for advocates of “traditional” marriage, this time in Utah, where a three-judge panel of federal appeals court heard a challenge to the state’s ban on same-sex marriage. It wasn’t a total rout — one judge plainly wanted to uphold the ban, one judge plainly wanted to strike it down, and the third seemed torn.

But a SCOTUS ruling is plainly coming, and by this time next year, we could have a final answer on the law. If and when that happens, the political fallout will be enormous.

If you’re a Republican party strategist, you may look a the prospect of a Supreme Court ruling enshrining gay marriage with some measure of optimism. Perhaps it’ll be like Roe v. Wade, you can tell yourself: it could create a backlash, giving Republicans an issue they can return to again and again to motivate their base and keep them coming to the polls. But that’s a dangerous place for conservatives to place their political hopes.

Of course, I’m assuming that the Court will rule in favor of marriage equality. I could be wrong, but given the lower court rulings and Anthony Kennedy’s decision in the DOMA case, a different outcome seems unlikely. The common thread running through these lower court cases is that marriage equality opponents have been completely unable to articulate any concrete harm done to straight people if gay people are allowed to marry. So even under the relatively low standard of “rational basis” review — where the state just has to have a rational basis for its policy discriminating against a particular group — the bans are likely to be struck down. If the Court decides that a higher standard of review is warranted, which it well might, it wouldn’t even be a close call.

So let’s assume for the moment that the Court takes one of these cases and strikes down the state bans. It would, without question, be a political earthquake.

Right now we could classify the states into three groups: the liberal states where marriage equality has already passed; the moderate states where bans passed at some point in the past but where opinion has shifted and such bans would fail today; and the conservative states, almost all in the south and midwest, where opposition to marriage equality is likely to remain a majority opinion for some time. In that last group, Republican politicians will decry America’s moral decay and the tyranny of black-robed despots, in tones that many will find uncomfortably close to the backlash after Brown v. Board of Education. In the 2016 election, the Republican base will turn out to cast a vote against gay marriage, voting for GOP candidates for all offices.

In some ways, it would be reminiscent of 2004, when a court ruling in Massachusetts legalizing same-sex marriage pushed the issue to the front of public consciousness, and Republicans successfully exploited it to boost turnout and win votes. But there will be a difference this time. The places in the country where that backlash will be felt most strongly are already firmly in Republican hands. If you’re in a state like Alabama or Kansas, where all the electoral votes are already going to the Republican candidate no matter what and all the statewide offices are already occupied by Republicans, an angry GOP electorate doesn’t get you much further benefit.

Right now, Republicans are faced with a dilemma. Their base is firmly opposed to same-sex marriage, and Republican politicians, whatever their personal views, must cater to that base. Their rhetoric may moderate as time goes on, but they have to keep sending the message that they are the party that opposes same-sex marriage. That’s true even though a majority of young Republicans support marriage equality; the true base is the older Republicans and evangelicals, and both those groups are strongly opposed.

So if and when the Supreme Court strikes down the country’s marriage bans, the GOP will have no choice but to condemn the decision in the strongest possible terms. In the short term — one election at most — they may gain some small benefit in turnout from the backlash in conservative areas. But their opposition will continue to hurt them with young voters and moderates, and only exacerbate their fundamental dilemma as the party of conservative older whites in a country that continues to move away from them, demographically and ideologically.

A Supreme Court ruling settling the marriage question won’t be like Roe v. Wade. There aren’t endless details we can litigate and legislate as there are with abortion; no one’s going to be trying to pass bills saying gay people have to get parental consent or wait 48 hours before getting married. And while public opinion on abortion has essentially been static for decades, opposition to gay marriage is rapidly dwindling and will never again be embraced by a majority of Americans.

So politically speaking, in the wake of a SCOTUS decision, the gay marriage issue will flare brightly, but much more briefly than abortion did. We won’t be debating it forty years from now. What will remain is the ill feelings among millions of voters toward a party they’ll view as intolerant for a long time to come.