Obama’s term has already seen the enactment of a federal law protecting gays and lesbians against hate crimes, an end to the ban on openly gay members of the U.S military and the issuance of a Supreme Court ruling striking down the law banning federal recognition of same-sex marriage. Such unions have now spread to 36 states across the country. A new Supreme Court ruling declaring same-sex marriage rights guaranteed by the U.S. Constitution could serve as the capstone on a record of change unparalleled on any other issue in the public eye during his tenure.

But precisely how much credit Obama deserves for the tectonic shift on the issue during his presidency is less clear-cut.

Many gay rights activists and historians see Obama as having been reluctant to put much muscle into gay rights causes early in his White House stay, but then warming to the topic as a result of outside pressure and a realization that rapidly changing public opinion made such moves politically advantageous. Some advocates say he’s added crucial momentum to the drive for “marriage equality” in recent years, while others say he’s still cautious on the subject and more inclined to be swept along by the public debate than to lead it.

That gay rights, and in particular same-sex marriage, could wind up as a hulking component of Obama’s legacy is a surprising development for a president who publicly snubbed same-sex marriage until nearly 3 1/2 years into his presidency and faced repeated complaints that he was shortchanging gay issues.

“He was late to the party, but he certainly made up for it,” said Richard Socarides, a New York lawyer and longtime gay rights advocate. “This is shaping up to be [Obama’s] most significant policy achievement of his entire presidency. He has certainly participated and, in some large measure I think, pushed forward the most significant gains in gay rights that we’ve seen in the history of the country.

“He’s done so sometimes begrudgingly, but I think that is the nature of the presidency,” the activist and former Clinton White House adviser said, noting the competing demands on a president’s attention.

Obama and his aides “were against it until they were for it, and then they really owned the issue and championed it in a way that was jaw-droppingly historic, and that’s what they’ll be remembered for,” said the Human Rights Campaign’s Fred Sainz.

Some historians, however, give Obama less credit and question how much the issue deserves to be seen as part of his legacy. They conclude that Obama has eased the country’s moves toward greater recognition of gay rights but hasn’t been at the forefront of them.

“The question is: Is he a leader or a follower?” asked Andrea Friedman, a history professor at Washington University in St. Louis.

“Obama has been carried along by public opinion and shifts in public opinion that have just accelerated so rapidly,” she said in answer to her own question. “I don’t see him necessarily as a leader or this as part of his legacy.”

When Obama marked gay pride month last year, he boasted about his record but was careful to temper the remark with an acknowledgement that the White House had often been nudged along on the issue.

“Because of your help, we’ve gone further in protecting the rights of lesbian and gay and bisexual and transgender Americans than any administration in history,” the president said.

The Supreme Court potentially extended that trend Friday when it announced that it has agreed to take up a set of cases that raise the issue of whether the U.S. Constitution guarantees all Americans the right to enter into same-sex marriages and whether states are obliged to recognize same-sex marriages performed in other states.

The outcome of the case is far from guaranteed, but many legal analysts believe the court’s liberal justices are likely to join with Republican appointee Justice Anthony Kennedy in a ruling that makes same-sex marriage available nationwide.

Early on, the president showed more timidity in his approach on gay rights. The administration’s strategy on the military’s “don’t ask, don’t tell” policy, for instance, involved prolonged consultations with the Pentagon. As a result, the project lingered until Democrats lost seats in the Senate and Obama’s overall policy agenda bogged down.

Legislation to repeal the “don’t ask, don’t tell” policy passed during Congress’s lame-duck session at the end of 2010, and the president claimed the bill as a triumph, but many activists quietly said the administration’s strategy was flawed and the measure only nosed over the finish line due to a last-minute push by the likes of departing Sen. Joe Lieberman (I-Conn.).

Once the law passed, however, advocates generally gave Obama high marks for its implementation, as well as for his appointment of a historic number of gay and lesbian officials to senior posts and judgeships.

Gay rights activists also credit the administration for taking a bold move in 2011 to dismantle the Defense of Marriage Act, the federal law President Bill Clinton signed in 1996 barring federal recognition of same-sex marriages. Attorney General Eric Holder, acting with Obama’s concurrence, announced the administration would no longer defend the law in court because there was no plausible argument to support its constitutionality.

“That was as game-changing as anything,” said former Rep. Barney Frank (D-Mass.), the first openly gay member of Congress. “Presidents always have to defend the constitutionality of legislation they dislike. For the president to take the position that DOMA was so blatantly unconstitutional and undesirable that he would take that unusual step [to abandon the law], that was the biggest deal of anything he did, and he deserved an enormous amount of credit for it.”

That decision drew howls of outrage from Republicans, but in a 5-4 ruling two years later, the Supreme Court struck the law down.

Gay rights activists welcomed Obama’s reversal on same-sex marriage in 2012, but he continued until last year to hold a nuanced stance on the legalities of the issue — arguably undercutting some advocates’ efforts to have the courts sanction same-sex marriage throughout the country.

In part to fend off Republican calls for a federal constitutional amendment banning same-sex marriage, Obama for years declared that marriage has traditionally been a state issue. Even when Obama’s evolution on gay marriage reached its apogee in 2012, he spoke of state-by-state experimentation on the issue as welcome.

“What you’re seeing is, I think, states working through this issue — in fits and starts, all across the country,” Obama told ABC’s Robin Roberts in an interview designed to showcase his change of heart on the subject. “Different communities are arriving at different conclusions, at different times. And I think that’s a healthy process and a healthy debate. And I continue to believe that this is an issue that is going to be worked out at the local level, because historically, this has not been a federal issue, what’s recognized as a marriage.”

In that interview, Obama also declined to quibble with North Carolina voters who had just agreed to insert a new ban on gay marriage in their state’s constitution.

Obama’s stance has long struck some advocates as misguided, since federal court cases striking down state bans on interracial marriage are at the core of civil rights jurisprudence and Obama once taught that subject at the University of Chicago. The approach also seemed to evoke a thread of the history of “states’ rights” resistance to federal anti-discrimination laws — an odd resonance for America’s first African-American president.

When litigation challenging California’s voter-approved same-sex marriage ban reached the Supreme Court in 2013, the Justice Department did not announce unequivocal support for a federal constitutional right to what advocates call marriage equality. Instead, Obama administration lawyers took the highly nuanced position that California could not deny same-sex couples the right to marry because the state already accorded such couples all the other privileges that go along with marriage.

Some analysts said the brief reflected a lack of courage on the administration’s part. Others said it was a strategic move aimed at making sure the court struck down the Defense of Marriage Act — a decision most easily reached by deferring to states.

“As a Republican looking at a Democratic president, President Obama’s equivocation on gay equality issues has always been really puzzling,” said Gregory Angelo of the Log Cabin Republicans, a gay GOP group that backs same-sex marriage rights.

When the Supreme Court announced Friday that it plans to wade into the issue of a federal right to same-sex marriage, the White House remained silent. In fact, on the eve of the announcement, White House press secretary Josh Earnest declined to state the president’s views on the legal issues, though the spokesman said the president would welcome wider availability of same-sex marriage.

Holder was more direct, announcing that the administration will urge the court to make same-sex marriage rights the law of the land.

“We expect to file a ‘friend of the court’ brief in these cases that will urge the Supreme Court to make marriage equality a reality for all Americans,” the attorney general said in a statement Friday. “It is time for our nation to take another critical step forward to ensure the fundamental equality of all Americans — no matter who they are, where they come from, or whom they love.”

Gay rights advocates say politics explain much of Obama’s reorientation from diffidence to active embrace of their positions. As public sentiment shifted on the issue, the administration saw opportunities to appeal to important constituencies by pushing an issue that differentiated Obama from most Republican candidates.

Prominent blogger and former Obama critic John Aravosis said Friday that he believes the administration’s change of approach on the subject became evident during the Democratic National Convention in 2012. Pushing gay rights there wasn’t just the right thing to do, or a move to satisfy gay activists, but projected tolerance in a way that appealed politically to female voters, young people and others.

“Since 2012, they’ve been embracing it,” Aravosis said, even describing the administration as “grandstanding” on the issue. “On the left, people talk about ours as one of the only progressive issues where [Obama] has had great success.”

“Once they understood that this was an issue that could work for them, they got fully behind it. That happened when he got reelected: They realized they could run on this, rather than run away from it,” added Socarides.

“Part of being president means you get to take credit for things that happen on your watch, and [Obama] came around and he was there when we needed him,” Socarides said, getting to the issue of whether Obama could claim the sweeping change on the issue as part of his legacy. “He definitely played a big part.”

Angelo said Obama deserves credit for embracing same-sex marriage rights even if that move came “later than it should have.” However, the gay GOP leader argued that the issue has been one where most politicians lagged, not led, the public.

“I don’t think any factor has been more important in influencing public opinion — and, I dare say, the opinions of the Supreme Court — than Joe and Jane American who happen to be gay and live down the street and are living their lives openly and honestly with their friends, neighbors and family members,” Angelo said. “It’s trickled up more than it’s trickled down.”

The advances on gay rights under Obama are so dramatic that The New Republic declared last October that he had become, in essence, America’s first gay president — a label that echoes author Toni Morrison’s branding of President Bill Clinton in 1998 as America’s first black president.

However, it’s also clear that Obama’s rejections of same-sex marriage continued to sting his own supporters and even close staffers all the way until his election to the White House. And even in 2004 — as he ran for the U.S. Senate at the age of 43 — he was unaware of the Stonewall Riots, a watershed 1969 event in the history of the fight for gay rights, according to “Winning Marriage,” a book by Marc Solomon of Freedom to Marry.

Frank said that dwelling on Obama’s self-described evolution on the issue misses a more basic fact: Without his nominees to the Supreme Court, the ruling expected in June wouldn’t even be conceivable.

“If he had not appointed [Justices Sonia] Sotomayor and [Elena] Kagan, and if John McCain had been president and had appointed two justices, there isn’t any room for doubt we would not have had the DOMA case and the issue wouldn’t be before them again,” Frank said. “None of this would’ve been on the boards right now.”