Debi Campbell is a grandmother of 12 and spent almost 17 years in a federal prison as a first-time drug offender. Learn how politicians are trying to end that practice. (Jeff Simon/The Washington Post)

At a time when partisans in Congress don't agree on anything, they have found one area where they can: Reforming America's sprawling and costly prison system.

Nearly 30 years after creating mandatory sentences for drug offenses, an unlikely band of lawmakers is moving forward with their plans to fix what they say is a broken criminal justice system.

At issue is a 1986 law designed to cut the drug crime rate in the United States by limiting the discretion of judges when it comes to prison sentences for drug offenses.

The result, according to advocates, is an overcrowded, expensive prison system filled with people with overly severe sentences.

The Senate Judiciary Committee is working through several reform bills crafted by lawmakers from the liberal and conservative wings of the two parties to put together a plan, which, they say, will help alleviate the financial and humanitarian costs of the spending guidelines.

So who are these unlikely co-sponsors?

Sens. Dick Durbin (D-Ill.) and Mike Lee (R-Utah) have joined forces and put together a bill that would give judges flexibility when they hand down sentences for nonviolent drug offenders. A House counterpart to the Durbin- Lee bill is co-sponsored by the unlikely duo of Reps. Raul Labrador (R-Idaho) and Bobby Scott (D-Va.).

Another bill, sponsored by Sens. Patrick Leahy (D-Vt.) and Rand Paul (R-Ky.) would expand that judicial leeway to some non-drug related crimes.

"I think money is driving this debate to some extent but also honesty," Durbin said in an interview. "After 30 years we ought to take a look at these laws. These aren't the 10 Commandments."

Overcrowded prisons have been increasingly a strain on federal budgets, costing an estimated $60 billion per year. Since the mandatory minimum law was implemented in 1986, the prison population has exploded -- from around 58,000 in the late 1980s to more than 217,000 in 2012, according to the Department of Justice and the Bureau of Prisons.

“People are starting to see the unfairness, people who have been kept in jail, sometimes 10, 20, 30, even 50 years for a non-violent crime,” Paul said in an interview. “I personally think if you made a mistake, a youthful mistake, that when you serve your time, and the time should be a reasonable time, that you should be able to get back into society.”

The timing of a reform bill is still uncertain, but Leahy, who chairs the Senate Judiciary Committee, indicated in a statement that a mark-up was in the near future.

"Doing nothing means cutting funding from law enforcement, victim services and crime prevention efforts -- doing nothing makes us less safe," he said. "We will soon be marking up legislation to address this important issue."

Labrador said House Judiciary Chairman Bob Goodlatte (R-Va.) has agreed to have a hearing in the House on the issue this year.

Lee says he sees natural common ground on the issue for progressive Democrats and libertarian-minded Republicans.

“The Senate is polarized in some areas and in other areas this is a great time for bipartisanship and this is one of those areas of building bipartisan consensus that we need reform in our federal system,” he said.

It's not the first time this issue has brought the two sides together.

The Fair Sentencing Act of 2010, that eliminated the sentencing disparity between crack and powder cocaine, was put together by Durbin and Alabama Republican Jeff Sessions as they worked out next to each other in the Senate gym. The bill eventually passed by unanimous consent.

The renewed legislative interest comes just months after the Obama administration announced changes to the sentencing guidelines for certain non-violent drug offenders, and Attorney General Eric Holder called on Congress to continue the effort by making reasonable changes to the law.

Julie Stewart, president of the pro-reform group Families Against Mandatory Minimums, said while the process has been slow, it has been positive for the movement.

“All of those steps have lead to this point where sentencing reform and over incarceration is no longer the third rail that it was even 10 years ago,” she said.

Jeff Simon contributed to this report.