Sen. Chuck Grassley Charles (Chuck) Ernest GrassleyThe Hill's 12:30 Report: Ginsburg lies in repose Top GOP senators say Hunter Biden's work 'cast a shadow' over Obama Ukraine policy Read: Senate GOP's controversial Biden report MORE (R-Iowa) said Thursday that Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellFEC flags McConnell campaign over suspected accounting errors Poll: 59 percent think president elected in November should name next Supreme Court justice Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' MORE (R-Ky.) should get on board with criminal justice reform legislation, arguing the Senate leader owes him for a wave of judicial nominations.

Grassley noted that Republicans have been successful at confirming Trump's judicial picks — including two Supreme Court nominees and a record number of appeals judges — adding that he felt he was owed "reciprocity" for his role in shepherding the nominees as Judiciary Committee chairman.

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"I look at this in a very personal way, Sen. McConnell and I have had a very close working relationship on judges. We've been very very successful. … We've made history and we've got two good people on the Supreme Court and I would like reciprocity from the leader on what I've done in our unified effort to get judges," Grassley said.

Grassley added that after President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE threw his support behind the criminal justice legislation, McConnell "ought to be helping the president get his program through."

Grassley's comments come as he and Sen. Dick Durbin Richard (Dick) Joseph DurbinFeinstein 'surprised and taken aback' by suggestion she's not up for Supreme Court fight Grand jury charges no officers in Breonna Taylor death Democrats shoot down talk of expanding Supreme Court MORE (D-Ill.) work to lock down support for forthcoming legislation that will merge a House-passed prison reform bill with a handful of changes to sentencing and mandatory minimum sentences.

The issue has been stuck in the Senate for years, despite having support from former President Obama, because of opposition from a small, but vocal, group of Republican senators. Supporters say they've had 60 votes for previous criminal justice reform bills, but McConnell has refused to bring them to the floor — a move that would have put a spotlight on divisions within the Senate Republican caucus.

McConnell was noncommittal when asked about the issue on Wednesday, saying supporters needed to show them they had the votes for the bill, which has not been introduced yet, to pass and then, once they did that, Republican leadership would weigh the bill against other end-of-the-year issues including preventing a partial government shutdown.

“We don’t have a lot of time left," McConnell said. "The first step is to finalize what proponents are actually for. There have been a lot of different versions floating around. And then we’ll whip it and see where the vote count is and then see how it stacks up against our other priorities going into the end of the session."

Sen. John Cornyn John CornynThe Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting Liberal super PAC launches ads targeting vulnerable GOP senators over SCOTUS fight Senate GOP faces pivotal moment on pick for Supreme Court MORE (R-Texas), a member of the Judiciary Committee and majority whip, echoed McConnell on Thursday noting senators don't have a lot of time until the end of the year.

“I would just note the obvious, and that is the short period of time we have during the lame-duck session," he said.