“The Willie Horton story is still part of the legend and lore of American politics,” said Senator Richard J. Durbin, Democrat of Illinois and one of the chief authors of the bipartisan Senate criminal justice proposal.

While the episode is almost three decades old, it still resonates in Washington, where some are quietly monitoring whether any drug offenders granted early release by the Obama administration in the fall quickly get back into trouble. At the same time, Democrats are leery that Republicans and their campaign allies could try to stick a soft-on-crime label on candidates who support the criminal justice legislation.

This Willie Horton dynamic makes clear what supporters of the legislation need to do if they hope to enact it into law this year: They must persuade leaders like Senator Mitch McConnell, the Kentucky Republican and majority leader who will decide if the legislation reaches the floor, that the politics of criminal justice have been upended and that the real political risk is to those who do not support the efforts. That could be a very steep climb.

“The politics of a presidential year threatens the issue, but I also think there will be consequences if Congress does not act,” said Holly Harris, the executive director of U.S. Justice Action Network, one of the groups promoting criminal justice changes. “These issues poll through the roof in support of reform. It is going to be our job to convince members that these are not only good data-driven policies, but they make for good politics.”

The high incarceration rate in the United States and an epidemic of drug abuse in some regions of the country have exposed more American families to the criminal justice system and the impact of mandatory minimum sentences, building a broader grass-roots base of support for the initiative. Promoters say new programs that would be instituted to help offenders return to their communities and get jobs actually help reduce crime — another selling point.