The Sentencing Reform and Corrections Act of 2015 (SRCA) is only the beginning of a series of massive sentencing reductions for convicts that progressive supporters want, said New Jersey Democratic Sen. Cory Booker on Tuesday, including the complete elimination of mandatory minimums.

“It’s never been the totality of what I wanted. It’s never been as bold as I wanted it to be,” Booker told Vox.com. “But it is a significant bill in the sense that it is stopping this drift that we’ve seen over the last 20, 30 years toward massive hyper-incarceration.”

What Booker is talking about when it comes to “massive hyper-incarceration” is unclear. The federal prison population has declined by 20,000 inmates in only three years, bringing it to its lowest level since 2006. As SRCA opponent Alabama Republican Sen. Jeff Sessions has said, it will likely drop by another 10,000 in a single year to lower it to 2004’s level. The Obama administration’s sentencing guidelines will eventually set free 46,000 prisoners to slash the federal prison population by a quarter — as crime levels rise.

Booker strongly opposes letting Americans affected by crime send representatives to Congress to ensure judges impose tough sentencing on criminals.

“[W]hat I reject is three strikes you’re out, 10-year mandatory minimums that take all the discretion out of the judge’s hands and put it all in the legislature’s hands. That’s one of the ways we’ve gone awry,” he said,adding:

In my opinion, I would have liked to just have gotten rid of the mandatory minimums altogether and made our judicial system about judges, juries, prosecutors, and defendants again and not legislators who know nothing about the particular circumstances of a case. So there’s a lot of things that are in the bill that aren’t the things that I really want, but it is a result of a compromise.

“I know federal judges who’ve spoken to the fact that they feel like their hands are tied, literally grieving that they have to put down sentences that they know are inappropriate,” he added later.

The progressive push to give judges total free reign on sentencing comes as President Obama is working hard to swing the judiciary left by appointing Democratic judges to federal courts. Liberal judges will be more inclined to give lenient sentences to criminals. Scrapping mandatory minimum sentences also leaves the door open for corruption: As Breitbart News’ Lee Stranahan has reported, judges can trade justice for political favors, as one judge in 1975 did, cutting a deal with Black Panther officials in exchange for their support in a mayoral race.

“[T]he coalition that we’ve helped foster around this issue, it isn’t going away either,” Booker warned. “Conversations with [senior vice president and general counsel of Koch Industries, Inc.] Mark Holden, with the Koch brothers, with Newt Gingrich, with others — everybody knows that there’s more work to do. So I don’t think you’re going to get any diminution in commitment from a lot of these interest groups, advocacy groups, and justice groups.”

Booker also hinted that the election of presumptive Republican nominee Donald Trump could derail the prison sentencing reduction movement backed by wealthy business donors and anti-incarceration advocates.

“But, again, you never know what can happen — who’s going to win the presidential election, who’s going to win the Senate, who will be elected in the House. So I think the right thing to do is to get a bill that may not go as far as we want to. But it’s in my lifetime the first reversal of mass incarceration in the federal level.”