The day some marriage-equality advocates have been waiting for, and some still fear, is finally here. On Friday the Supreme Court accepted a petition to rule on the constitutionality of gay-marriage bans in Kentucky, Missouri, Ohio and Tennessee. The Court repeatedly declined to take up the issue in the last year, but a split among the appellate courts—those of the Fourth, Seventh, Ninth, and Tenth Circuits have previously ruled gay-marriage bans unconstitutional, but in November the Sixth Circuit broke from the pack—was widely viewed as having forced the justices’ hand.

“The Supreme Court’s decision today begins what we hope will be the last chapter in our campaign to win marriage nationwide—and it’s time,” said the president of marriage-equality group Freedom to Marry, Evan Wolfson, widely considered the father of the gay-marriage movement. “America is ready for the freedom to marry.”

While the justices’ decision to take the case invites speculation about how the Court will rule, it should come as little surprise. A year and a half ago, the Supreme Court set off an avalanche of litigation with its ruling in United States v. Windsor, in which the justices struck down Section 3 of the Defense of Marriage Act, which prohibited the federal government from recognizing same-sex marriages performed in the states. While Windsor did not explicitly address the constitutionality of such unions, in eliminating the ban Justice Anthony Kennedy wrote that it was intended “to disparage and to injure those whom the State, by its marriage laws, sought to protect in personhood and dignity.” Since then, dozens of courts have overturned state-level bans on gay marriage, reasoning that Kennedy’s language makes such laws constitutionally suspect.

But their justification for striking down such laws has varied widely. If the sentiment behind Kennedy’s ruling is clear, his legal reasoning was vague; he did not address whether gay couples had a “fundamental right” to marry or whether gays and lesbians constituted a class of people in need of judicial protection from discrimination. The Court also sought, in however perfunctory a way, to limit the scope of its decision; the majority opinion made clear that the Court was not deciding the same-sex marriage issue.

But Justice Antonin Scalia, the Court’s conservative firebrand, saw through the majority’s half-hearted assurances. “The real rationale of today’s opinion, whatever disappearing trail of its legalistic argle-bargle one chooses to follow, is that DOMA is motivated by ‘bare…desire to harm’ couples in same-sex marriages,” Scalia wrote. “How easy it is, indeed how inevitable, to reach the same conclusion with regard to state laws denying same-sex couples marital status?”

As evidenced by the string of victories for gay-marriage advocates that followed, pretty easy indeed.

But Kennedy’s vagueness also left room for some conservative justices, and the right-leaning Sixth Circuit, to reason that the Court’s 1972 ruling in Baker v. Nelson—in which the justices upheld a Minnesota law limiting marriage to heterosexual couples—was still the controlling precedent, thus setting the issue up for a rematch down the line. In the opinion of some legal analysts, this was Kennedy’s plan all along.

With gay marriage already legal in thirty-five states and with Justice Kennedy—the author of the two landmark gay-rights rulings of the last two decades, Windsor and Lawrence v. Texas, which overturned state bans on sodomy—as the swing vote, there’s little doubt how the Court will rule.

The legal wrangling over same-sex marriage draws to a close just as the race for the presidency gets under way. While major contenders for the Democratic presidential nomination have all stated their support for marriage equality—or in the cases of New York Governor Andrew Cuomo and Maryland Governor Martin O’Malley, actively championed the cause—none of the Republicans considering a presidential run have followed suit.

The irony is that, ten years after using gay marriage as a wedge issue against John Kerry in the 2004 election, it is the GOP for whom the issue poses a threat. Public opinion on gay marriage has swung dramatically: in 2004, a mere 30 percent of Americans supported same-sex marriage; today, nearly 60 percent do. It’s been called the largest turnabout on any social issue in American history. Support is even higher among young Americans, and even a majority of young Republicans support same-sex marriage.

But older conservative voters remain decidedly opposed, which has left Republican presidential hopefuls like Jeb Bush to triangulate. Shortly after courts struck down Florida’s ban on gay unions, Bush conceded, however grudgingly, that gay marriage was here to stay. “We live in a democracy, and regardless of our disagreements, we have to respect the rule of law,” he said. “I hope that we can also show respect for the good people on all sides of the gay and lesbian marriage issue—including couples making lifetime commitments to each other who are seeking greater legal protections and those of us who believe marriage is a sacrament and want to safeguard religious liberty.”

For a politician who once said “sodomy” should not have “the same constitutional status as race and religion,” it was a frank acknowledgment that the ground has shifted. No Republican candidate who hopes to win the GOP primary can fully get on board the gay-marriage bandwagon lest he upset the party’s older voters, but no candidate who staunchly opposes gay unions can hope to win the presidency by going against the grain of public opinion.

By this time the next president assumes office—thirty years after the Hawaii Supreme Court set off panic nationwide by ruling the state could not deny gay couples the right to wed—same-sex marriage will be legal in all fifty states. Anyone who hopes to lead the country must reconcile herself to that fact.