The words “we apologize for slavery” never have made their way into a formal resolution by U.S. lawmakers to be signed by a sitting president. Those words seemed no closer to making it to President Barack Obama’s desk for signature as he and other leaders paid tribute Wednesday to Americans who, a century and a half ago, helped bring about an end to slavery.

“The scars of our original sin are still with us today,” Obama said Wednesday as lawmakers marked the 150th anniversary of the abolition of U.S. slavery. “In America, we can create the change that we seek. All it requires is that our generation be willing to do what those that came before us have done.”

But the speeches given by Obama and congressional leaders during the ceremony marking the passage of the 13th Amendment made no mention of America's long debate over reparations as a way to atone for 245 years of enslaving black Americans. Not even the first black commander in chief, in the final stretch of his presidency, has formally apologized for the nation’s generations-long slave trade, a gesture that could clear the way for some form of compensation to slave descendants, proponents have said. While Congress has worked for years on the language of a formal apology and reparations, opponents and critics have said the idea would create racial rifts over the cost and would be nearly worthless without targeted actions that address slavery’s lasting legacy of socioeconomic inequality for blacks.

“We have yet to eradicate the badges and vestiges of slavery, so it is very appropriate that the conversation for reparations be resurrected around the anniversary,” Ron Daniels, president of the Institute of the Black World 21st Century, said in a phone interview Wednesday. The group, which has offices in Maryland and New York, this year formed the National African-American Reparations Commission and called on Obama to establish a slavery reparations task force to study ways to implement compensation through executive order.

“At all levels, people are fearful of justice,” Daniels said. “There’s a fear that because you have apologized, you will have to remedy that which was damaged. But an apology, frankly, is just the first stage.”

Critics, however, argue that forcing all American taxpayers to pay reparations would further isolate the black community by fueling new racial tensions among nonblacks who claim they didn’t reap any of the benefits of slavery. “Are we saying, if your skin is black, you’ll get paid,” David Horowitz, head of the conservative values group Freedom Center in California and author of a book on the controversy over reparations, said in a phone interview. “The people who are advocating it are either ignorant of the history or they are racist and want to divide Americans.”

Democratic and Republican members of the House and Senate, including several members of the Congressional Black Caucus, participated in Wednesday’s commemoration in Emancipation Hall of the U.S. Capitol. Sen. Tim Scott, an African-American Republican from South Carolina, and Rep. Steny Hoyer, a white Democrat from Maryland, were among a half dozen lawmakers to read an official history of U.S. enslavement and the Civil War battles that spurred the constitutional amendment bringing it to an end.

“We should be honest with ourselves -- it took centuries of cruelty and injustice” for the U.S. to realize that slavery was wrong, said House Speaker Paul Ryan. “But today we celebrate the moment when our country decided: Yes, they should be free.”

The 13th Amendment, in part, reads: “Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.” But the country’s leaders have never coalesced around a formal apology for the practice and institution that saw millions of Africans and their descendants enslaved on plantations in the U.S. South and elsewhere in the nation.

In 2008, 143 years after ratification of the 13th Amendment, the House voted by unanimous consent to issue an apology to African-Americans for the institution of slavery. That apology included Jim Crow segregation laws that relegated many blacks to second-class citizenship for nearly 75 years. The following year, the Senate also passed a resolution apologizing for slavery. Those apology resolutions never made it to Obama’s desk for signature because neither chamber could agree on language that would exempt the U.S. from future claims for slavery reparations by black Americans.

But advocates of reparation argue recognizing the black contribution to national development through some form of compensation is crucial to ending decades of inequality and healing deep wounds. Racial disparities in wealth, education, healthcare, land ownership, employment, housing and municipal and social services that continue to plague communities today have their roots in slavery, said reparations proponent Robert Widdell, an associate professor of history at the University of Rhode Island in Kingston, whose research is centered around African-American social justice movements.

“The failure to address such issues after the end of slavery was the basis for the Civil Rights and Black Power movements 100 years later,” Widdell said. A lack of progress on those African-American socioeconomic issues is also fueling the Black Lives Matter social justice movement, he added.

But in a 2014 rejection of U.S. slavery reparations, Richard Epstein, a teaching fellow at the politically conservative Hoover Institution at Stanford University in California, argued that no wealth survived the demise of slavery and Jim Crow. “None of it was shared gratuitously with the rest of the nation,” Epstein wrote in an essay. “As a general matter, virtually all the wealth that exists in the United States today has been created by the ingenuity of a dizzying array of inventors, entrepreneurs, immigrants, and countless others.” Making immigrants, whose ancestors did not participate in slavery, claim responsibility for the scourge of slavery isn’t fair, he and other opponents have argued.

Obama has grappled with the nation’s legacy of slavery before. In 2013, he visited Senegal’s Goree Island, the last place that slaves landed before crossing the Atlantic to North America.

goree island U.S. President Barack Obama arrives by boat to tour Goree Island, including the House of Slaves, or Maison des Esclaves, off the coast of Dakar, June 27, 2013. Photo: Saul Loeb/AFP/Getty Images

“Obviously, it’s a very powerful moment … to come here and to fully appreciate the magnitude of the slave trade, to get a sense in a very intimate way of the incredible inhumanity and hardship that people faced before they made the Middle Passage and that crossing,” Obama said following a tour of Maison des Esclaves on Goree Island. But even with his understanding of the magnitude of the slave trade, Obama has been seen as reluctant on taking an official stance on issues as divisive as slavery reparations, said Dan Berger, assistant professor of comparative ethnic studies at the University of Washington in Bothell.

“Words alone are insufficient,” said Berger.