WASHINGTON — Twenty-five years ago, after passing the most sweeping anti-crime bill in history, Democrats were ecstatic, convinced they’d not only addressed a top concern of voters but finally shed the party’s soft-on-crime label.

That was then.

A quarter century after Joe Biden helped shepherd it into law, the legislation has become a point of fierce contention among Democrats and emerged as a likely flash point in the series of presidential debates that begin Wednesday night in Miami.

Some consider the law too tough and many, including President Trump, blame it for a wave of mass incarceration that has filled prisons with a flood of black and brown inmates.

“It destroyed entire neighborhoods, destroyed entire communities and we’re still paying the price and suffering from it,” said Patrisse Cullors, a Los Angeles activist who co-founded the Black Lives Matter movement. “What people need to say is, we made a mistake. A very big one.”

Majority Whip James E. Clyburn of South Carolina, a veteran of the civil rights movement and the highest-ranking black member of Congress, is among the strongest defenders.

“The fact of the matter is we on the Democratic side did a yeoman’s job in putting in the kind of prevention programs, the preventive funding in the bill,” Clyburn, the No. 3 leader in the House, said on CNN.

The passions surrounding the bill and its legacy reflect a dramatic shift in the public mood — due in no small part to a significant drop in crime — as well as changes in a Democratic Party that has moved dramatically leftward as young people and minorities gain political strength.

It also underscores the generation gap between the 76-year-old Biden and younger rivals focused on the racial and social injustices that grew from the push for stiffer punishment.

“Awful,” New Jersey Sen. Cory Booker told the Huffington Post.

“A huge mistake,” said New York City Mayor Bill de Blasio.

Trump, eliding his history of racially inflammatory words and deeds, has echoed the attacks. “Anyone associated with the 1994 Crime Bill will not have a chance of being elected,” he taunted Biden on Twitter. “In particular, African Americans will not be able to vote for you.”

Biden, who led the Senate Judiciary Committee and has referred to the law as the “1994 Biden crime bill,” says there were parts he opposed in the all-or-nothing package, including mandatory sentencing under a “three strikes, you’re out” provision for repeat offenders.

(The Democratic front-runner will take the stage Thursday night, in the second of two debates.)

Overall, Biden insists the good far outweighed the bad.

“It’s the one that had the assault weapons ban,” he told voters in New Hampshire. “It limited the number of bullets in a clip. It made sure that cop-killer bullets, Teflon bullets, weren’t available any longer. It opened up the whole effort to make sure there is background checks for the first time in American history.”

The legislative package also included the Violence Against Women Act, landmark legislation that capped years of efforts to toughen laws against rape, stalking and domestic abuse.

“Anyone who says it was a terrible bill doesn’t know what else was in the bill,” said former California Sen. Barbara Boxer, a liberal who joined all her fellow Democrats, save one, in support. (Seven Republican senators also backed the legislation, which passed 61-38.)

The legislation came at a time when crime, fueled by street gangs and the crack cocaine epidemic, was seen as spiraling out of control — including in Washington, D.C., under the very noses of congressional lawmakers.

Democrats were acutely sensitive to the issue. Bill Clinton ended the party’s exile from the White House by running in 1992 as a “different kind of Democrat,” with a tougher approach to law enforcement — the Arkansas governor even briefly dropped off the campaign trail to preside over the execution of a cop-killer with severely diminished mental capacity.

When the bill finally passed, after several close calls, Democrats exulted.

“This could be one of those turning points in history,” the Senate majority leader, George Mitchell of Maine, told reporters. “I think … the time is over when, in fact or perception, the Republicans are seen as the party that’s tougher on crime. It’s the Democrats.”

The 356-page bill — formally known as the Violent Crime Control and Law Enforcement Act of 1994 — was, like many products of compromise, a legislative grab bag.

There was funding for “midnight basketball” leagues, to keep at-risk youth from trouble, and billions of dollars to build prisons and encourage longer sentences.

There was a ban — since expired — on 19 types of assault-style weapons; funding to hire 100,000 police officers; an expansion of the federal death penalty, and money to establish “drug courts” to steer users away from jail into long-term recovery programs.

It was neither a progressive piece of legislation nor a draconian crackdown, said Franklin Zimring, a University of California, Berkeley law professor who has written extensively on criminal justice issues. “It was everything.”

There was no lack of support among African Americans.

Dozens of pastors backed the measure along with black mayors. So, too, did most of the Congressional Black Caucus, though some came around only after the vote was cast as life-or-death for the politically floundering Clinton. The bill was also sweetened with millions of dollars in spending for cities sought by African American lawmakers.

Even so, some black leaders, including the Rev. Al Sharpton, were vigorously opposed. “We were attacked for being soft on crime,” he said nearly 25 years later. “We were saying it was unfair and racially unbalanced.”

The NAACP called it “a crime against the American people.”

Still, the bill passed the House 235-195, with most Democrats in favor and most Republicans opposed. (Presidential hopeful Bernie Sanders, a Vermont independent then serving in the House, voted in support despite some reservations.)

Two decades on, both sides can marshal facts to press their respective cases: That the bill led to mass incarceration and also resulted in lower crime rates.

Neither is entirely true nor false.

Crime rates were already falling by the time the bill passed, as the crack epidemic waned and the economy recovered from the recession of the early 1990s. A report by the Government Accountability Office, released in 2005, said the hiring of an additional 88,000 police officers between 1994 and 2001 produced only a “modest” drop in crime.

Nor was the bill wholly responsible for increased incarceration.

Prison populations began climbing in the 1970s and grew at a rapid clip in the 1980s. However, by offering billions in federal funding, the bill did create incentives for states, which house the majority of inmates, to build more prisons and impose stiffer sentences.

Clinton expressed his regrets in a 2015 speech to the NAACP, as his wife, Hillary, prepared for her second presidential run. “I signed a bill that made the problem worse,” he said of the trend toward increased incarceration, “and I want to admit that.”

Not Biden, though he has disavowed 1986 legislation he co-sponsored that imposed vastly harsher sentences for crack cocaine — which was associated with poverty and urban blight — than powdered cocaine. The weight fell disproportionately on black and brown Americans.

“It was a big mistake that was made,” Biden said at a January breakfast marking the Martin Luther King Jr. holiday. “We were told by the experts that ‘crack, you never go back,’ that the two were somehow fundamentally different. It’s not. But it’s trapped an entire generation.”

In 2010, President Barack Obama signed legislation — the Fair Sentencing Act — that ended the sentencing disparity. As vice president, Biden helped push the measure through Congress.

Los Angeles Times staff writer Michael Finnegan contributed to this report.