WASHINGTON (Reuters) - Republicans and Democrats in the U.S. Senate scrambled on Thursday to save an effort to overhaul America’s prison policies and criminal sentencing standards, seen as a bipartisan win just weeks ago, but now up against a major obstacle.

FILE PHOTO: A prisoner walks with the aid of a stick at the California Medical Facility prison in Vacaville, California, U.S., May 23, 2018. REUTERS/Lucy Nicholson/File Photo

Republican Senate Majority Leader Mitch McConnell, who controls the chamber’s agenda, has not brought up the legislation for a vote, even though it is backed by President Donald Trump and perhaps more than 70 senators, depending on who is counting.

High political stakes ride on the outcome, which some lawmakers see as a test of Congress’ ability to pass any kind of bipartisan policy reform, even with White House support.

With the Democrats taking over the House of Representatives in January and Republicans keeping their grip on the Senate, bipartisanship will be needed to get much done in 2019-2020, even if hyper-partisanship has been the norm in recent years.

Entitled the First Step Act, the bill would make it easier for deserving inmates to be released from prison into halfway houses or home confinement, create programs to reduce recidivism, and prevent first-time non-violent offenders from facing harsh mandatory minimum sentences.

As time for action runs short, conservative groups supporting the First Step Act are inundating McConnell’s office with letters and phone calls.

The “lame-duck” session of the current Congress is expected to end before Christmas. The 2019-2020 Congress will be seated on Jan. 3. Backers of the measure feel now is the time to enact the legislation, given its broad bipartisan backing in Congress and support by the White House and among interest groups.

Waiting for next year, they fear, could give opponents more time to pick apart the current legislation.

For now, McConnell is not budging, under pressure from conservative Senate Republicans opposed to the prison and sentencing reform measure, such as Tom Cotton and Ted Cruz.

“There is a singular obstacle preventing that bill from getting a vote on the Senate floor, and that’s Mitch McConnell,” said Representative Hakeem Jeffries, an architect of the bill and the newly elected House Democratic Caucus chairman.

“That is outrageous,” Jeffries told Reuters in an interview. “If he were to be successful in preventing an incredibly bipartisan bill on such an important issue from reaching a vote in the Senate, that would be an indictment of the broken democratic system that we have in Washington right now.”

A McConnell spokesman referred questions to remarks the leader made in mid-November, when he said: “The first step is to finalize what proponents are actually for. ... And then we’ll whip it and see where the vote count is,” he said.

WHITE HOUSE ALLY

A joint project of Jeffries and Republican House colleague Doug Collins, as well as Republican Senate Judiciary Committee Chairman Chuck Grassley and No. 2 Senate Democrat Dick Durbin, the bill also has a key White House ally.

Jared Kushner, Trump’s son-in-law, has advocated for the bill for months. “This bill would have been dead in May but for Jared Kushner’s persistence and really smart strategy,” said a lobbyist for a conservative group that backs the legislation.

A son of privilege from New York City, Kushner nevertheless has personal experience with the issue from visiting his father in prison. Charles Kushner served 14 months for tax evasion, illegal campaign contributions and witness tampering.

Earlier this year, Jeffries and Collins pushed a version of the bill through the Republican-controlled House. It focused solely on prison reforms and lacked sentencing reforms, a structure meant to win support from Republicans who, like Cotton in the Senate, fear sentencing reforms could put more violent criminals on the street.

Last month, Trump unveiled a new version at the White House. It combined the House-passed bill with sentencing measures backed by Grassley and Durbin, intended to win backing from libertarians, Christian conservatives and progressive Democrats.

In remarks just nine days ago in Mississippi, Republican Senator Lindsey Graham praised Kushner and said the bill would get 80 votes if it were brought to the Senate floor.

On Thursday, Republican Senator Mike Lee, a bill proponent, said there were 28 hard “yes” Republican votes plus 49 Democrats for the bill. “It’s rock-solid,” he said.

But Senator John Cornyn said more Republicans needed to be convinced. “Right now we have a majority of the Republican conference either undecided or no,” he told reporters. He also continued to call for some changes to the bill.