President Obama appeared on a jumbo screen at the 2015 Grammy Awards in Los Angeles just a few moments after the crowd had been rocking out to an arrangement of Pharrell’s relentlessly upbeat earworm “Happy.” Obama changed the tone.

“Nearly one in five women in America has been a victim of rape or attempted rape, and more than one in four women has been a victim of domestic violence,” Obama said. “It’s not okay. And it has to stop.”

The appearance was a surprise, but it shouldn’t have been completely unexpected, given how much attention the Obama administration had paid to the issue of sexual violence — and to pursuing changes in both policy and culture — for years.

Soon after taking office, Obama had called on every department in the government to make fighting sexual assault and domestic violence a priority. He released a series of White House reports. He and Vice President Joe Biden gave passionate speeches. And the White House even teamed up with comedy websites to release goofy online videos meant to appeal to young men.

The result was a quiet but widespread war on sexual violence that reached college campuses, the military, Indian reservations, and local police departments. It wasn’t a silver bullet solution, but the incremental changes (substantive and cultural) marked the beginning of one of the most significant efforts by any presidential administration to take on sexual assault in the United States.

Sexual violence is a problem deeply entrenched inside our society, institutions, and attitudes. Stamping out such a problem, advocates acknowledge, requires a concerted effort to change not just laws but hearts and minds — a project that could take years and decades. It requires vigilance. Advocates fear that the momentum built in the past eight years will stall in the era of Donald Trump.

Trump, of course, was caught on tape bragging about grabbing women without their consent and once suggested on Twitter that sexual assault in the military is the inevitable result of allowing women to serve. He will be guided by a chief strategist, Steve Bannon, who was once charged with domestic violence and whose website, Breitbart.com, portrayed accusations of sexual assault (except when allegedly committed by Bill Clinton) as mostly a buzzkill for football and fraternities.

Trump can’t undo all the policy changes the Obama administration put in place, or those passed into law by Congress. Nor can he reverse the cultural changes that helped push those federal initiatives forward. But his election represents a powerful symbolic shift. Trump hasn’t just been silent on his plans to address sexual assault in America — he’s embodied many of the values the Obama administration spent eight years trying to combat.

“It would be difficult for [Trump] to erode any of the actual substantive changes that have occurred over the last three years,” said retired Col. Don Christensen, the president of Protect Our Defenders, a group focused on military sexual assault. “What he could do — and we hope he doesn’t do — is send the wrong message.”

How Obama waged a war on sexual assault on college campuses

During Obama’s presidency, the Education Department opened hundreds of investigations into how colleges handle sexual assault on campus, forcing schools to change their policies to provide more support to victims.

This started with a letter the Education Department sent to colleges in 2011. The letter reminded them that Title IX, the law better known for increasing women’s participation in sports, requires schools to investigate reports of sexual assault on campus. The law forbids gender discrimination on campus, and courts have interpreted sexual assault as a form of discrimination because the fallout can interfere with students’ education.

The Education Department also directed colleges to use a lower standard of proof — “the preponderance of the evidence,” meaning at least a 51 percent chance that the accused did it — in sexual assault investigations. This was a significant change on many campuses.

The letter didn’t have the same force as a new law or regulation. But it told colleges how the federal government was going to interpret Title IX. Colleges found out of compliance with Title IX can lose their federal funding, a punishment so severe that it’s sometimes called the death penalty in education circles.

Over the next five years, more students started to come forward to report their assaults. And Congress passed a law as part of the Violence Against Women Act requiring colleges to make data on sexual assault, stalking, and dating violence public, and to educate new students about how to prevent sexual assault.

Some critics, including congressional Republicans and the Foundation for Individual Rights in Education, argued that these measures went too far, and that colleges were trampling on the due process rights of male students who had been accused of sexual assault. (The Education Department recently announced that Wesleyan College had, in fact, violated Title IX by discriminating against a student this way.)

The 2011 letter, though, empowered activists. As victims of sexual assault organized and demanded policy changes, getting more media attention to their cases, the Obama administration’s policy backed them up by sending a message that there could be consequences for colleges that didn’t act.

And the greater publicity led to a growing number of investigations: In 2009, when Obama took office, the Education Department received just 11 complaints related to mishandling of sexual assault. Five years later, in 2014, it received 102. (Multiple studies and surveys, including several conducted in recent years, have found that between one in five and one in four women is sexually assaulted while in college.)

But while the Education Department’s work on campus sexual assault got the most attention, it wasn’t the only way the Obama administration tried to make changes. Other efforts tackled sexual assault in the military, changed how police departments and the FBI approach the issue, and even attempted to shift the culture.

How the Obama administration tried to change the FBI, local police, and American culture

The Obama administration’s broader fight against sexual assault started with what might have seemed like just a symbolic gesture.

In March 2009, Obama, who had won a bigger share of women’s votes than any previous presidents, created the White House Council on Women and Girls, a committee that includes every Cabinet agency.

Creating a committee doesn’t always get results. But, Obama said in October 2010, he’d directed every agency to come up with ways to address domestic violence and sexual assault. The result was a long list of policy changes and new laws, some dealing with domains where men are more likely to be victims than women:

The Defense Department required that victims of sexual assault in the military have access to a lawyer.

The FBI updated its definition of rape — which the agency defined until 2013 as “carnal knowledge of a female forcibly and against her will” — to reflect a more modern understanding of the crime: “penetration of the vagina or anus … without consent.”

The Department of Justice ordered prisons and jails to do more to prevent and punish sexual assault among inmates or risk losing federal funding.

All federal agencies were required to develop policies on sexual assault, harassment, and stalking among their own employees.

A federal grant program helped communities deal with giant backlogs of untested rape kits and trained police to interact more sensitively and effectively with victims of sexual assault.

Congress, at the urging of the Obama administration, passed a new law allowing American Indian tribes to prosecute rape and domestic violence committed by non-Indians.

In at least one area, the Obama administration largely disappointed advocates: sexual assault in the military. Reports of sexual assault in the military have increased sharply — the Pentagon received a total of 6,083 reports of sexual assault in fiscal year 2015 — and the majority of victims are men.

While military policy did change to be more supportive of victims, it was at the behest of Congress, not the president.

In 2015, as part of a defense spending bill, Congress took away the right of military commanders to overturn sexual assault verdicts. The new laws got rid of troops’ ability to defend themselves against assault accusations by arguing that they had “good military character.” And they added protections on mental health records and resources for military spouses and children who were assault victims.

Activists and lawmakers, including Sen. Kirsten Gillibrand, are still seeking bigger changes, including taking military commanders out of the decision-making process. But Obama, while frequently speaking out about military sexual assault, generally declined to make those changes by executive order.

The changes Obama did make in other policy areas — from Indian reservations to the FBI — didn’t always get much media attention. But the overall result was incremental and meaningful progress that put victims’ interests front and center.

How the Trump administration could roll back these efforts

Some of the changes made in the past eight years are here to stay. The FBI definition of rape is unlikely to be changed. Congress will still require colleges to report statistics about rape on campus and offer preventative education, and the changes Congress made to the military are here to stay as well. Grants to local agencies for rape kits and police training that have already been doled out aren’t going to be taken back, even if the Trump administration is uninterested in continuing those programs in the future.

But the centerpiece of Obama’s fight against sexual assault — the increased pressure on colleges — is particularly vulnerable to being dismantled.

Trump could simply eliminate the pressure by getting rid of the Office of Civil Rights, the part of the Education Department that enforces Title IX. His campaign policy director suggested during the campaign that he’d like to do just that, moving it to the Department of Justice. But that would face fierce resistance and be legislatively difficult.

The more likely scenario is that Trump’s Education Department simply reverses the guidance from the 2011 letter, which doesn’t have the force of a law or even a regulation.

This kind of change isn’t unprecedented. President Bill Clinton made it relatively difficult for colleges to escape Title IX penalties by arguing that women on campus didn’t want to play sports. President George W. Bush made it easier, and Obama shifted back to Clinton’s standard.

Trump could direct colleges to use a higher standard of evidence, such “clear and convincing” proof, to find a student responsible for sexual assault. Congressional Republicans have already tried to make it harder for colleges to find men guilty of sexual assault, pushing to change the standard for finding students guilty from “preponderance of the evidence” to the more rigorous “clear and convincing evidence.”

Or Trump’s Education Department could simply stop using those guidelines and let colleges return to any standard they wanted. At least some colleges — which have faced lawsuits from students found guilty of sexual assault as well as those who were victims of it — would welcome the reduced scrutiny.

Trump didn’t address the issue on the campaign trail, so it’s hard to say what he’ll do in office. Either way, though, the student activists who put campus sexual assault on the national agenda in the first place aren’t going away. College sexual assault isn’t only an issue because the Obama administration pursued it — it’s now widely regarded as a national crisis.

But while student activists can only threaten a college with bad publicity, the Education Department investigations could end by cutting off all federal funding. The question is whether students’ activism, without the force of Trump’s federal government behind them, would be enough.

The Obama administration didn’t just change policy. It tried to change rape culture.

Perhaps the most radical thing the Obama administration did on sexual assault might not have been a grant program or a policy change. It was Obama’s, and particularly Biden’s, willingness to continually, publicly challenge and try to change widespread attitudes that make men believe they’re entitled to women’s bodies.

The most eloquent statement of these principles came from Biden in June, when he wrote an open letter, published on BuzzFeed News, to the victim of a sexual assault at Stanford University:

You are a warrior — with a solid steel spine. I do not know your name — but I know that a lot of people failed you that terrible January night and in the months that followed. Anyone at that party who saw that you were incapacitated yet looked the other way and did not offer assistance. Anyone who dismissed what happened to you as “just another crazy night.” Anyone who asked “what did you expect would happen when you drank that much?” or thought you must have brought it on yourself… What you endured is never, never, never, NEVER a woman’s fault… We will speak to change the culture on our college campuses — a culture that continues to ask the wrong questions: What were you wearing? Why were you there? What did you say? How much did you drink? Instead of asking: Why did he think he had license to rape? We will speak out against those who seek to engage in plausible deniability. Those who know that this is happening, but don’t want to get involved. Who believe that this ugly crime is “complicated.” We will speak of you — you who remain anonymous not only to protect your identity, but because you so eloquently represent “every woman.”

But even before Biden’s statement, the Obama administration was trying to live out its principles.

The president, vice president, their wives, and members of the Cabinet refused to visit colleges they believed had mishandled sexual assault, the Washington Post’s Juliet Eilperin reported in July. The “It’s On Us” initiative, which Obama appeared at the Grammys to promote, was a public service campaign that urged everyone — particularly men — to step in if they saw someone being harassed or assaulted.

And Obama and Biden spoke frequently and forcefully about men’s responsibilities not just to avoid sexual assault themselves, but to dismantle the attitudes that made society take it less seriously.

This is where President Donald Trump — who was accused of sexual assault by 15 different women during the last month of his campaign — could provide the most dramatic contrast. Trump defended his comments as “locker room talk.” That’s an attitude that, months before the Access Hollywood tape leaked, Biden had specifically condemned.

“You guys in the audience, we’ve gotta overcome this social discomfort of calling out the misogyny that happens when no women are present: the locker room talk, the bar banter, the rape jokes,” Biden said in June.

This is what some advocates are the most worried about: Instead of a president and vice president who forcefully talk about men’s responsibilities to change the culture that permits sexual assault, there will be a president who has repeatedly downplayed its realities and consequences.