Updated

Saying that Americans can't close their eyes anymore, President Obama called Tuesday for bipartisan action to revamp a criminal justice system riddled with inequities that result in unduly harsh prison sentences, particularly for minorities, and cost the government billions for unwarranted mass incarceration.

"In far too many cases, the punishment simply does not fit the crime," Obama told a crowd of more than 3,000 at the NAACP's annual convention.

"Mass incarceration," he added, "makes our country worse off and we need to do something about it."

Obama ticked off statistics showing that the U.S. prison population has quadrupled since 1980 and doubled in the last two decades alone.

The costs "cannot be measured in dollars and cents" alone, he said, pointing to the disproportionate impact on blacks and Hispanics.

"There's momentum building for reform," Obama said, pointing to growing interest from both Republicans and Democrats on Capitol Hill and around the country.

He spoke one day after he commuted the sentences of 46 drug offenders, 14 of whom had been sentenced to life.

Despite the new interest among Republicans in criminal justice legislation, not all GOP legislators saw the president's commutations as a positive step.

"Commuting the sentences of a few drug offenders is a move designed to spur headlines, not meaningful reform," said Rep. Jim Sensenbrenner of Wisconsin, a member of the House Judiciary Committee who has proposed bipartisan legislation.

In the Senate, Judiciary Committee Chairman Chuck Grassley, R-Iowa, said in a statement that he's been working toward bipartisan agreement on broad legislation that could include reductions in mandatory minimum sentences "in certain situations."

Since Congress enacted mandatory minimum sentences for drug crimes in the 1980s, the federal prison population has grown from 24,000 to more than 214,000, according to Families Against Mandatory Minimums, a group seeking sentencing changes.

And the costs, Obama says, are over $80 billion a year to incarcerate people who often "have only been engaged in nonviolent drug offenses."

"Congress simply can't act fast enough," said Julie Stewart, president and founder of Families Against Mandatory Minimums. She said that while Obama's executive actions have picked off some of the most egregious sentencing inequities, significant legislative action is needed to stop the flow of people "going to prison year in and year out, serving too much time."

Support from tough-on-crime Republicans in any such effort is critical, Stewart said, likening it to a Nixon-goes-to-China moment.

Todd Cox, a senior fellow at the Center for American Progress, a liberal advocacy group, said there was momentum from both ends of the political spectrum to address the over-criminalization that has "resulted in people being put in prison who frankly shouldn't be there." His group is part of the Coalition for Public Safety, whose members and backers range from the liberal American Civil Liberties Union to the conservative Koch brothers.

In recent years, as the crime rate has dropped, long drug sentences have come under increasing scrutiny and downward trends already are taking shape.

The Supreme Court has made sentencing guideline ranges advisory rather than mandatory. Obama signed the Fair Sentencing Act in 2010 to cut penalties for crack cocaine offenses. And last year, the independent Sentencing Commission, which sets sentencing policy, reduced guideline ranges for drug crimes and applied those retroactively.

Overall, Obama has commuted the sentences of 89 people, surpassing the combined number of commutations granted by the previous four presidents. But that's still a sliver of all those seeking clemency: Justice Department statistics show that roughly 2,100 commutation petitions have been received so far this fiscal year, and about 7,900 are pending.