For much of Barack Obama’s presidency, he has steered away from the topic of race, and stopped short of making criminal justice reform a top White House priority. But on Tuesday, weeks after giving an emotional eulogy on race in Charleston, South Carolina, Obama’s long-awaited call for sweeping criminal justice at the NAACP annual convention was just what his audience in Philadelphia wanted to hear, at the moment when they wanted to hear it.

The NAACP president, Cornell William Brooks, called it an “extraordinary address”.

“He spoke about forgiveness, about grace and also about smart criminal justice policy – because this unforgiving, ungraceful policy that we have right now is both expensive and stupid,” he said.

Gary Bledsoe, 61, an NAACP board member and the president of the organization’s Texas state conference, said Obama’s bipartisan, outspoken call was “courageous”.

“For him to reach out and be above the fray – and even commend the Koch brothers is significant. It shows he’s really about doing things to make a difference and not just to solidify his legacy,” he said.

Calling for an end to mass incarceration and for wholesale changes in a system that “by a wide margin … disproportionately impacts communities of color,” the president described the criminal justice system as “an aspect of American life that remains particularly skewed by race and by wealth”, and “a source of inequity that has ripple effects on families and on communities throughout our nation”.

Obama didn’t announce any new executive orders from his own office on Tuesday, instead expressing support for sentencing reforms already proposed in Congress. But that more than satisfied many racial justice advocates longing to hear Obama acknowledge the scope of the problem and lend his public support.

Hilda Rodgers, 68, a delegate from New York City was impressed by the speech, noting that it “addressed the issues that we are already addressing individually in our respective communities”. Claude Cummings Jr, 63, a delegate from Houston, said: “I’m excited and I enjoyed the speech but the question is now: what’s going to happen?”

The speech was delivered just one day after the president commuted the sentences of 46 federal prisoners convicted for nonviolent drug offenses, and appears to be part of a larger late-presidency push to make progress on an issue that enjoys a unique degree of bipartisan support. Obama noted several times in his address the “unlikely bedfellows” that reform has brought together, like senators Corey Booker and Rand Paul who introduced legislation in March aimed at keeping nonviolent offenders out of prison. “You’ve got Americans for Tax Reform and the ACLU, you’ve got the NAACP and the Koch brothers!”Obama said to laughter from the audience.

In fact many of the statistics the president shared with the convention audience in making the case for action were identical to the ones published by the Coalition for Public Safety, a bipartisan group that counts the Koch-backed Freedomworks and the progressive thinktank Center for American Progress among its founders. Among them: the the cost of mass incarceration. “Every year we spend $80bn to keep folks incarcerated,” Obama said. “For what we spend to keep everyone locked up for one year, we could eliminate tuition at every single one of our public colleges and universities.”

The president also made several paeans to law-enforcement officials and prosecutors – taking pains to make clear that criminal justice reform does not mean a mass-exodus of criminals from correctional facilities. “If we’re gonna deal with this problem and the inequities involved then we also have to speak honestly – there are some folks who need to be in jail,” Obama said.

Speaking before one of the nation’s oldest and most venerable civil rights organizations, President Obama honed in on the stark racial disparities in the criminal justice system that have increasingly been a part of racial discourse in the country.

“A growing body of research shows that people of color are more likely to be stopped, frisked, questioned, charged, detained,” the president said. “African Americans are more likely to be arrested, they are more likely to be sentenced to more time for the same crime.” President Obama framed much of his speech around three distinct realms where reform was needed: “the community, the courtroom and the cellblock”.

On the last of the three, the cellblock, the president took an unequivocal stance against overuse of solitary confinement, a practice he said had the potential to make inmates “more alienated, more hostile, potentially more violent”. Obama indicated he had asked the attorney general, Loretta Lynch, to begin a review of the practice nationwide.

The speech came just days before Obama is scheduled to become the first sitting president to visit a federal correctional facility. Thursday, Obama will continue his push on criminal justice reform by visiting the El Reno prison in Oklahoma, a medium-security facility that houses 1,300 inmates. The prison once held Jason Hernandez, a Texas man who had been been serving a life sentence for drug crimes until the president commuted his sentence in 2013.

The Oklahoma NAACP chapter president, Anthony Douglas, is ecstatic that the president is visiting his state in conjunction with his criminal justice reform push. Asked about what he expects from the visit, Douglas said: “I think he’s going to look at the reason why people are in here, and he’s not just going to look and see this is a good, secure facility. I hope he looks at the inmates who are incarcerated in this prison and says ‘why are they here?’” Douglas also said he hopes the visit might highlight the fact that Oklahoma incarcerates more women than any other state in the nation.

President Obama closed his address to the convention, the second of his presidency, by likening the challenge of achieving criminal justice reform to a footrace and urged making progress step by step. “That’s how you win a race, that’s how you fix a broken system, that’s how you change a country,” Obama said.