WASHINGTON — Current and former prosecutors are the group most likely to push back hardest and loudest on bipartisan changes to the criminal justice system expected to be formally proposed in the Senate soon, despite the Justice Department’s insistence that federal prosecutors are on board with Obama administration plans to make the drug war less about doling out prison time.

Mike Lee, a Republican senator from Utah, is not one of those former prosecutors. The former U.S. Attorney has been working for years to change criminal justice rules to make the system, he says, fairer, safer and more cost-effective. And he doesn’t have much interest in the complaints of prosecutors who don’t think change is a good idea.

“We make the laws, it’s our business to make the laws,” Lee said in an interview about his criminal justice efforts with BuzzFeed News in his Capitol Hill office last week. “It’s their business to enforce them.”

Republicans are, more and more, embracing a position on criminal justice progressive advocates have been pushing for decades. Lee has been a leader on the GOP side, prodding lawmakers to embrace the so-called smart on crime movement (as opposed to the tough on crime movement of old) ever since he witnessed drug prosecutions as a member of federal law enforcement.

“One example that sticks out involves a defendant who was convicted of a couple of counts of, I think it was possession with intent to distribute,” Lee recalled, citing a case he didn’t personally handle but witnessed first hand as a young prosecutor. “He was in his twenties. It involved a couple of sales of marijuana, not huge quantities. But because of the way the mandatory penalties operated together, he ended up getting some unbelievably long sentence. I think it was a 55-year sentence. He won’t be out of prison until he’s 80.”

“My reaction was not at the time and still is not now, ‘This guy didn’t do anything wrong.’ He did. But it’s very different saying he deserved a 55-year sentence,” Lee went on, recalling that the judge in the case wrote an unusual opinion lamenting that the law prevented him from sentencing the defendant to fewer years. “That has stuck with me. And so when I got here, I thought I ought to try to do something about that system.”

Lee, 44, is young for a senator, and his pathway to the Senate was based in the libertarian-leaning section of the tea party movement often embraced by younger conservatives. There’s a younger vibe to his office than most Senate chambers. His office has been Mac-only since he first arrived in 2011, and at least one of his senior staffers can be found tapping away on a MacBook at a standing desk awkwardly affixed to the dark wood office furniture common to the Russell Senate Office Building. Lee’s staff is relatively young, too, and they appeared to have the easy-going relationship with their boss in the few minutes of a senior staff meeting BuzzFeed News stumbled into while on a recent visit.

This is not to suggest Lee is a moderate by any means: He enjoys a 100% ratingfrom the American Conservative Union as well as the Club For Growth.

That’s all in keeping with the criminal justice advocacy movement on the right, which has often been led by policymakers closely tied to the most conservative wings of the Republican party. For these Republicans, the evangelical movement’s focus on morality, the tea party’s focus on slashing government spending and the libertarian movement’s focus on a perceived strict adherence to the Constitution all require a criminal justice system that doesn’t throw the book at nonviolent drug offenders. Instead, it would try to steer them toward treatment programs for addicts and more inexpensive correction programs like probation. The general idea is that whatever punishment is doled out should fit the crime.

Even among criminal justice advocates, Lee remains on the conservative side. He does not favor an end to all mandatory minimum sentences, for example, a position that puts him to the right of some advocates. “I am for reforming them,” he said. “What’s happened is that it has been kind of a one-way ratchet. … If all you’re doing is creating new mandatory minimums and then increasing them once they’ve been created, and you never look at rolling them back for being afraid of being called soft on crime, you’re going to end up with some problems. And that’s where we are.”

Keeping some mandatory minimum sentences, slashing others and perhaps creating some new ones are all part of the negotiations going on in the Senate right now. Lee declined to say which mandatory minimums he likes, preferring to focus on the ones he wants to see reformed. Like most advocates, he was specifically critical of mandatory minimums tied to the amount of drugs an offender is caught with, saying they can result in low-level drug couriers being slapped with many more years than the distributor who dispatched them.

Criminal justice negotiations in the Senate are delicate, even with the changes in the GOP led by politicians like Lee. Powerful Republicans who spent decades leading the tough on crime movement remain wary of smart on crime policies that run counter to the narrative about drug crime — that more and harsher sentences are the only way to reduce it — even as they move away from the policies of the past. Democrats and the White House are trying to push these Republicans into a compromise, as is an unlikely coalition of conservative groups and progressive advocates.

Observers on all sides say Lee is among the hardest-working politicians in Washington when it comes to criminal justice. He’s in regular contact with administration officials, advocates and Democrats and is often mentioned as a key figure in the success advocates have begun to see in the Republican-controlled Senate.

Lee has been talking about criminal justice since he first arrived in Washington back in 2011. A freshman senator talking about putting fewer criminals in jail did not exactly find a lot of a lot of allies among old-guard Republicans at first, he recalled.

“A lot of it was just deaf ears. People just didn’t want to talk about it,” Lee said. “It was like they were hearing elevator music. It just wasn’t something they felt like talking about.”

Lee chalks up the shift in the GOP to successes in red states and a growing body of statistics that he says prove crime rates and long prison sentences for nonviolent drug offenders are not tied together. He eventually used some of those ideas to craft the Smarter Sentencing Act with Illinois Democratic Sen. Dick Durbin, a bill that codified many of the ideas supported by advocates on both sides and the White House.

“Over time, we fine tuned the message. And when the message became coupled with a concrete legislative proposal that nobody can dismiss as crazy, that’s where it really started gaining momentum,” Lee said. “We had to talk about it, we had to talk about it a lot, we had to talk about it publicly. It’s hard to measure, but there’s kind of a critical mass — people have to hear it, I don’t know, 5, 10, 15 times before it starts to register. I’m not criticizing anyone, it’s just human nature. You have to hear it enough times for it to set in.”

The legislative proposals, the language tuning and the state successes gave Lee and other Republican criminal justice advocates a chance to reframe the debate in their party, he said.

“Nobody wants to be soft on crime, and that’s a fear that a lot of people have had,” Lee said. “So that’s a hurdle that we had to overcome, especially with Republicans, was persuading them that this is not an effort to be soft on crime. This is an effort to be smart on crime. To be more effective on crime.”

The ongoing debate is between supporters of “front-end changes” to the justice system — the elimination of mandatory minimum sentences and creation of new methods for prosecuting first time nonviolent drug offenders that steer them away from prison entirely — and “back-end changes” like post-prison job training programs and supervised probation that supporters say reduce recidivism and, eventually, lower the prison population because of it. Back-end changes are an easier lift, politically, while front-end changes are the real goal of advocates.

Lee dismissed the idea that political concerns could quash legislative front-end changes to the justice system in proposals expected to get votes in the Senate this year.

“That’s not going to happen. We’re going to get some of both. We may not get everything I want,” he said, “We may not get all of the Smarter Sentencing Act reforms. But I think we will get a lot of them, perhaps most of them.”

That Washington is a desert of partisanship and the criminal justice advocacy movement an oasis of comity has become cliché at this point. But according to Lee, the constant bipartisan meetings on Capitol Hill, the White House meetings between senior administration officials and Koch-funded advocates and the constant stream of public forums in Washington featuring firebrand liberals and conservatives all preaching the same message aren’t just for show. Lee praised Democrats, liberals and the White House — “The president has reached out to me personally,” he said — for leading on criminal justice issues and said current efforts couldn’t be done without them.

“My Democratic colleagues have done a very good job at maintaining an open mind and being willing to negotiate,” Lee said.

Progressive Democrats who may want more changes to the front end of the system than the current Senate will allow probably won’t blow things up, Lee said. “I don’t see signs of that,” he said. “They have negotiated in good faith. It’s been difficult, it’s been very difficult, but because we feel — and when I say we, I’m with a lot of the Democrats on this issue — we feel very strongly that what we proposed in the Smarter Sentencing Act is very reasonable, and it should be something we could agree to pass into law right now.”

The bipartisan focus, he noted, comes from the bipartisan creation of the modern drug war in the first place. It wasn’t that long ago that the combined criminal justice efforts of prominent Republicans and Democrats established longer, harsher prison sentences for anyone caught with narcotics and funneled billions of dollars for new prisons to house the huge wave of offenders pulled into the system as a result.

Some politicians who were active in those years have begun to express public regrets for the tough on crime era. For politicians like Lee, who weren’t making laws in the 1980s and 1990s, moving away from the policies of that time is easier, but still a chance to redress what he said were mistakes with grave consequences.

“When you’ve got points that are difficult or impossible to refute, when you point out for example that our federal prison population has increased eight or nine fold since 1980," Lee said. "When you point out statistics like that. Those points go unrefuted because they’re irrefutable in and of themselves.”