WASHINGTON — Supporters of a federal criminal justice system overhaul seemed well on their way to victory after legislation breezed through the House last week on an impressive bipartisan vote. It has strong Trump administration backing, including the imprimatur of Jared Kushner, the presidential adviser and son-in-law who is eager for a progressive policy win, as well as important friends in the Senate.
There is just one problem: Senior Senate authors of a long-stalled but much more comprehensive criminal justice package are steadfastly opposed to the alternative plan. They consider it an insufficient half-measure for its focus on prison programs without changes in federal sentencing laws. And they have the clout — and perhaps the votes — to stall it, if not block it altogether.
In a private huddle on Wednesday on the Senate floor, a group of senators corralled Senator Mitch McConnell, Republican of Kentucky and the majority leader, and asked for time for a last-ditch negotiation to try to find an acceptable compromise. Quite rightly, backers of changes in mandatory minimum laws fear that this may be the only chance for years to push a major criminal justice measure through Congress and that sentencing revisions — a more politically difficult lift — will languish if legislation aimed at reducing prison recidivism becomes law on its own.
“You don’t get many opportunities around here to do anything meaningful or substantive,” said Senator Richard J. Durbin, Democrat of Illinois and a chief author of the sentencing provisions. “Let’s not waste this one. Let’s get this right.”
Mr. Durbin has a powerful ally in Senator Charles E. Grassley, Republican of Iowa and the chairman of the Judiciary Committee. Mr. Grassley came around slowly to sentencing changes, but once he got on board, he has been committed. He warned again last week that no criminal justice measure can pass the Senate without new flexibility in mandatory minimum sentences.
“It’s the right thing to do,” Mr. Grassley said in a speech.
Mr. McConnell could try to go around Mr. Grassley and advance the House measure, which passed 360 to 59. It allocates $50 million a year over five years for job training, education and mental health and drug treatment, and provides incentives for prisoners to take part in the programs.