Some of America’s most bitterly divided political organizations, untangling from mortal combat over the role of government and the presidency, have agreed to set aside their disagreements and join forces in a drive to tackle the country’s addiction to mass incarceration.

On one side of the divide are the Koch brothers, the energy tycoons who have used their vast wealth to fund rightwing conservative policies and candidates. On the other is the Center for American Progress, the progressive thinktank founded by John Podesta, the outgoing White House adviser who left the administration last week to spearhead Hillary Clinton’s bid to succeed President Obama.

While the powerful groups will soon return to spending their billions against each other in the 2016 presidential race, they have agreed to bury the hatchet – and spend a few million – on criminal justice reform.

Together with a spate of funding bodies and thinktanks from both right and left of the political spectrum, they have formed the Coalition for Public Safety. Launched on Thursday, it plans over the next few years to lobby for legislative changes at both federal and state level that the groups hope will reduce the US prison population, cut prison budgets and lead to greater fairness for all Americans.

The new alliance will combine the financial might of Koch Industries, the brothers’ company, with prominent philanthropic funders that include Laura and John Arnold, the conservative body Right on Crime and the John D and Catherine MacArthur foundation. On a Thursday call with reporters, the director of the coalition, Christine Leonard, said the initiative reflected “our desire to get past the differences between us and find solutions”.

Speaking from the left-of-center, Neera Tanden, president of the Center for American Progress and a former Clinton adviser, admitted that she was “much more used to debating some of the leaders of this coalition than joining them”. But she said there was a united determination to tackle the unintended consequences of a criminal justice system that had increased the US poverty rate by 20% between 1980 and 2004.

On the right, Matt Kibbe, president of the Tea Party-alligned and Koch brothers-funded FreedomWorks, said the new alliance “marks a potential shift in the traditional left versus right, Republican versus Democratic split. That suggests that something big is going to happen on criminal justice reform.”

The coming-together of such strange bedfellows is a reflection of how the crisis of criminal justice in America has spread alarm across all political persuasions. Over the past 30 years, the prison population has risen relentlessly to more than 2 million people, by far the highest number in the world. The annual cost of incarceration is now $80bn a year, while one in three Americans have criminal records.

Those kinds of statistics please neither the right, which likes to talk tough on crime but is also wedded to balancing budgets and small government, nor the left, with its accent on justice and equal treatment under the law. The passage through Congress of legislation such as the 2010 Fair Sentencing Act, which reduced the racially significant disparity between punishments for crack and powder cocaine, and the Death in Custody Act, which introduces a federal record of deaths in police custody, have shown that incarceration – and perhaps incarceration alone – is able to pierce through the partisan gridlock of Washington.

In an address last week, outgoing attorney general Eric Holder said the US needed to confront an “over-reliance on incarceration”.

“While old habits are hard to break, these numbers show that a dramatic shift is under way,” Holder said. “I believe we have taken steps to institutionalize this fairer, more practical approach such that it will endure for years to come.”

Several state legislatures, including several in the deep south such as Alabama, Georgia, Mississippi and Texas, where the criminal justice system faces some of the most severe challenges, have also embraced a bipartisan approach to reform in recent months.

Some outside monitoring groups remained skeptical about the true motivation of the Koch brothers, however, in attaching themselves to the new bipartisan push. Lisa Graves, who has investigated the Kochs as the leader of the Center for Media and Democracy, pointed out that as a major backer of the American Legislative Exchange Council (Alec), the brothers have helped to spread policies across the states such as “three strikes and you’re out” that have helped to inflate the incarcerated population and encourage the proliferation of private prisons throughout the country.

“Criminal justice reform is long overdue but Alec fueled the crisis with Koch Industries as a leader of it. Now the Kochs want to take credit for trying to solve a problem they helped cause,” Graves said.

Certainly, the sums involved in funding the new coalition are miniscule for the Kochs, who are estimated to be worth $50bn each. The backing for the alliance begins at $5m, shared among various partners include the billionaire brothers.

By contrast, the Kochs alone are estimated to have spent about $100m backing rightwing candidates in November’s midterm elections. They have set a budget of nearly $900m for the 2016 campaign.

But the previous track record of the brothers has not dissuaded prominent groups from joining the alliance. Anthony Romero, executive director of the American Civil Liberties Union, said he was “thrilled” to find common cause with Koch Industries.

“We finally have the wind in our backs. It’s taken over 40 years to build this addiction to incarceration, and now we need to undo it,” he said.

One of the earliest issues that the coalition is likely to tackle is civil forfeiture – the controversial practice by police forces that takes money and property from individuals without having to prove any crime has occurred. Legislation to restrict such programs is seen as potentially attractive to members of Congress from both main parties.