The bipartisan criminal justice overhaul bill that advanced Monday evening falls short of what lawmakers and advocates had sought to do with the measure more than four years ago — but now that’s the key to enacting the most sweeping changes to prison and sentencing laws in decades.

The latest version, on the floor via an unrelated bill, is whittled down to the provisions with the broadest support, bulked up with measures demanded by law enforcement and tough-on-crime Republicans, and tweaked to get the backing of President Donald Trump.

It’s a “compromise of a compromise,” as California Democrat Sen. Kamala Harris put it when announcing her support for the bill Monday. And senators who back the bill and a wide ideological spectrum of outside groups who long fought for the measure spent Monday asking the Senate to reject even more changes that they say could fracture a delicate deal.

The Senate voted 82-12 in a procedural vote Monday, setting up votes later in the week on three amendments from Republican Sens. Tom Cotton of Arkansas and John Kennedy of Louisiana that would narrow the scope of the bill even more. Those amendments would need a simple majority to be adopted. A final vote will follow.

“Our understanding is that superficially the amendments don’t gut the heart of the bill — but they’d risk fracturing some parts of the coalition, throwing final passage into doubt,” said Ames Grawert, senior counsel in the Brennan Center’s Justice Program.

Another advocacy group, #cut50, signed onto coalition letters at the federal level, organized a letter of state-based criminal justice groups and encouraging crime victims’ rights groups to reach out to senators.

“Our focus today is educating members on the harmful provisions in these amendments and giving them reasons and cover to vote ‘no,’” said Alex Gudich, #cut50 deputy director.

Among other changes, the main bill aims to lower the number of federal inmates through changes in some sentencing laws and through better support for prisoners returning to society so they don’t commit new crimes and return to prison.

Cotton said the bill allows early release for many categories of serious, violent criminals and that is a threat to public safety as well as the future election prospects for Republicans who support it. Kennedy has said sentencing changes in his state have decreased public safety.

Amendments

One Kennedy-Cotton amendment would add nine offenses to a list of those that prevent inmates from qualifying for a program that would allow them to serve a latter part of their sentence in a halfway house or home confinement. And it would exclude any prisoner serving more than a year sentence on a crime involving violence, which would be most violent offenders.

Grawert called that “incredibly short sighted” because 95 percent of all incarcerated people will be released one day. “Would you rather they be encouraged to reform themselves and learn a skill while incarcerated — or not?” Grawert said.

The other amendment would add language to require the Bureau of Prisons to notify victims before a prisoner is released and make public data about how many inmates commit new crimes when in early release from prison.

The latest version of the bill, released last week, includes new measures to address points raised by the National Sheriff’s Association, such as preventing firearm offenders and fentanyl traffickers from early release from prison and specifying conditions for supervised release from custody.

“Our focus has always been to reduce crime and recidivism and improve fairness in a way that promotes safety and respect for the law,” Senate Judiciary Committee Chairman Charles E. Grassley said on the floor last week. “We could not have done this without the essential input from a number of key law enforcement organizations that partnered with us in this endeavor.”

Grassley had been a staunch opponent of the criminal justice push in 2014. The White House didn’t invite him to a meeting with key lawmakers on the issue, even though he chaired the committee with jurisdiction over it. Religious leaders in his state published opinion pieces urging him to change his mind. His state’s largest newspaper ran an editorial calling his rhetoric “dismissive and defensive.”

Within a year, Grassley emerged as a lead negotiator about to introduce legislation incorporating some of previous bills’ key ideas and demonstrated how the Senate can still, sometimes, hammer out compromises. He stuck with that compromise even as Trump and other Republicans pressed for a bill without sentencing changes, and called out Majority Leader Mitch McConnell when he declined to put the measure up for a floor vote this month.

All votes against the procedural motion Monday were Republicans.

Bipartisan accomplishment

Now, as Grassley departs to take the gavel at the Finance Committee, the bill is a chance for the 115th Congress to deliver a signature policy accomplishment. On the floor before the vote, Grassley gave credit to his colleagues and Trump and called it “the product of years of negotiating and listening to each other.”

Majority Whip John Cornyn of Texas, who introduced a version of the prison overhaul bill in 2015 along with Rhode Island Democrat Sen. Sheldon Whitehouse, said on the floor Monday that he believes the bill has enough supporters to get to the president’s desk.

“We’ve all learned how to get things done here in the Senate, and that is not just to point out the problems with legislation, but it’s also to listen and work together to find solutions,” Cornyn said. “And that’s exactly what we did.”

The bill’s main provisions include modest changes to sentencing. It would give judges more freedom to hand down sentences below the mandatory minimum for nonviolent drug offenders. It would reduce mandatory minimums associated with the three-strikes law.

It would eliminate a provision that prosecutors used to “stack” firearm charges for long sentences for first-time offenders. And it makes retroactive a 2010 law that reduced the sentencing disparity between crack and powder cocaine.

On the prison side, the bill would create more job training and drug treatment for inmates, among other changes. The bill would increase direct spending by $346 million over the next 10 years, according to the Congressional Budget Office.

The bill, if it becomes law, won’t end the call for criminal justice changes.

Sen. Richard J. Durbin of Illinois, the Democrat who wrote the bill with Grassley, said on the floor Monday that he agrees with those who suggest the bill doesn’t go far enough to unwind harsh mandatory minimums. But compromise is what the Senate is all about, he added.

“Congress should make this bipartisan legislation a fitting ending to this year,” Durbin said. “For all the cynicism and skepticism about what Congress can achieve, we can prove as soon as tomorrow, with one of the most historic changes in criminal justice legislation in our history, that we can work together for the good of this nation.”