Among advocates campaigning to reduce the country’s bloated prison population and invest in rehabilitation, there is a growing sense that a) Congress is unlikely to pass anything this year worthy of being called reform, and b) it might be better to start over in 2017.

Even the decidedly modest reforms that had some momentum a few months ago – measures that would mainly reduce mandatory minimum sentences for some drug offenders – have run into fierce opposition from law-and-order hawks such as Sen. Tom Cotton, R-Ark, who credits mandatory minimums for the 25-year decline in violent crime.

Major reform still has a formidable array of advocates. President Obama yearns to make justice reform part of his legacy and has lobbied for it in public and in private. House Speaker Paul Ryan has also professed support, as a way of slowing the community-destroying cycle of poverty, crime and punishment, not to mention a way of demonstrating that the GOP is not indifferent to the blacks and Latinos who are disproportionately ground up in the current system. Reform is backed by a strange-bedfellows alliance of conservative and progressive interest groups and by many big-city law enforcement officials. And a new poll released Thursday by the Pew Charitable Trusts finds strong public support for reducing or even eliminating mandatory minimum sentences and letting prisoners earn time off their sentences by participating in programs like job training and drug counseling.

Supporters of reform are mobilizing a last-ditch assault on Capitol Hill, hoping to convince lawmakers that reform is a matter of public safety and fiscal prudence. They are pinning some hopes on Ryan, on endorsements from police chiefs and prosecutors, and on the fact that everybody is still actively negotiating. “The clock has not run out,” said one congressional aide. Gloomier advocates say that even if Ryan delivers in the House, it would take a near-miracle to get anything bold through the Senate.

Some reform proponents believe the best they can expect is that Congress will grant a very narrow reprieve for one group of crack cocaine offenders. Back in 2010, Congress reduced sentences for inmates who were punished under a law that treated crack cocaine far more severely than powder cocaine. (The most conspicuous difference between the two forms of the drug is that powder is more popular with white users, while crack users tend to be black.) An estimated 5,800 people convicted before 2010 remain imprisoned. Congress could make these prisoners retroactively eligible for a judicial review of their sentences.

In the absence of legislation, President Obama will surely come under pressure to use his powers of executive clemency aggressively in his final days. Thousands of federal prisoners have applied to have their sentences commuted, but the cases are backed up in a processing pipeline.

If reform dies on Capitol Hill, the autopsy is likely to identify several causes of death.