Ta-Nehisi Coates and Danny Glover join renewed debate over reparations on Capitol Hill

Steps away from the U.S. Capitol – a building built by slaves – the House Judiciary subcommittee on the Constitution, Civil Rights and Civil Liberties held its first hearing in more than a decade on the hot-button topic of reparations for the descendants of Africans brought to America, enslaved and impacted by discriminatory policies including segregation.

The hearing, timed to coincide with "Juneteenth," a date when the last slaves in Texas learned they were free, brings to the forefront the centuries-old debate over what, if anything, is owed.

At the end of the Civil War formerly enslaved families were promised by Union leadership 40 acres and a mule -- an offer never fulfilled. Centuries later, the debate over reparations is playing out on the campaign trail as many 2020 presidential presidential candidates weigh in on the topic and lawmakers press the case with perennial legislative efforts.

The appearances of actor Danny Glover and award-winning author Ta-Nehisi Coates, whose 2014 essay "The Case for Reparations" thrust the divisive topic onto the national stage and lent celebrity status to an issue that has been wending through Congress for decades.

Glover grew emotional as he spoke about his family's history as sharecroppers and as the descendants of slaves and stressed that America needs to acknowledge the impact of slavery and discrimination.

"James Baldwin, the great writer once said, 'if we can't tell the truth about the past, we become trapped in it," Glover told the panel. "This country is trapped in not telling the truth."

Former Rep. John Conyers, D-Michigan, first introduced reparations H.R. 40 legislation in 1989 aimed at creating a commission to "make recommendations concerning any form of apology and compensation to begin the long-delayed process of atonement for slavery." The measure has been reintroduced every congressional session since then and was re-introduced this year by Democratic Rep. Sheila Jackson Lee of Texas.

The measure has drawn support from NAACP President Derrick Johnson whose organization backed the measure starting in 2014.

"Here we are in 2019 talking about it again. It is a sore spot for this nation," Johnson told ABC News in April. "It is something that we must address, so we can get past this moment in time in a way in which the legacy of slavery, the legacy of segregation, the legacy of institutional racism can once in for all be done away with and we can all prosper as a nation as one whole community."

Dr. Julianne Malveaux, a noted economist, spoke at the hearing about her family being lynched on land that they owned and forcibly removed.

"Reparations is an idea whose time has come," she told ABC News before the hearing.

Many 2020 Democratic presidential candidates have tackled the issue head-on, with the majority weighing in at several presidential forums this year including Rev. Al Sharpton's annual National Action Network convention.

Jackson Lee's bill has more than 50 cosponsors, including at least three House Democrats running for president: Eric Swalwell of California, Tim Ryan of Ohio and Tulsi Gabbard of Hawaii.

Gabbard was one of the earliest 2020 candidates to sign onto H.R. 40. She worked as a congressional legislative aide to her mentor the late U.S. Sen. Daniel Akaka of Hawaii, who in 1993 spearheaded a resolution, passed and signed into law by President Bill Clinton, apologizing for America's illegal role in overthrowing Hawaii's Queen Lili'uokalani in 1893.

Gabbard, in an interview in New Hampshire with WMUR, talked about reparations: "I think something similar needs to take place for other indigenous people and for the dark tragedy of slavery that occurred in our country's history.”

In early April, Sen. Cory Booker, D-N.J., held a joint press conference with Rep. Jim Clyburn, D-S.C., to promote a 10/20/30 funding bill outside of the U.S. Capitol, a measure that seeks to allocate 10% of federal funds to invest into counties that have had a poverty level of at least 20% for over 30 years.

When asked by ABC News if the bill was a form of reparations Booker declined to comment, but Clyburn, the dean of the South Carolina congressional delegation, said that he "absolutely" feels it is.

Days later, Booker tweeted that he planned on introducing H.R. 40 in the Senate as part of a companion bill.

At the hearing on Wednesdsay, Booker said "I feel a sense of anger where we are in the United States of America, where we have not yet had conversations about a lot of the root causes of the inequities, and the pain and the hurt manifested in economic disparities. Manifested in health disparities. Manifested in disparities a criminal justice system that is indeed a form of a new Jim Crow."

He continued, "we as a nation have not yet acknowledged and grappled with racism and white supremacy that has tainted this country's founding and continues to persist in those deep racial disparities and inequalities today."

Another 2020 candidate who's been talking about reparations since 1997 is spiritual leader Marianne Williamson, who told ABC News Monday, "The whole idea of reparations, to me, has been an extension of a moral principle."

Williamson said reparations tackles "the economic gap that existed at the end of the Civil War and has never been closed."

Williamson added: "The reason I feel strongly about reparations is because there is an inherent mea culpa, there's an inherent acknowledgment, that a wrong that has been done."

While support for the measure has gained momentum among several 2020 candidates, the Senate's most prominent Republican, Majority Leader Mitch McConnell, voiced blunt opposition to the idea of reparations on Tuesday.

"I don't think reparations for something that happened 150 years for whom none of us currently living are responsible is a good idea," McConnell told reporters at a press conference. "We've tried to deal with our original sin of slavery by fighting a Civil War, by passing landmark civil rights legislation, by electing an African American president."

He said that another issue is that it would be hard to "figure out" whom to compensate.

"We've had waves of immigrants, as well, who have come to this country and experienced dramatic discrimination of one kind or another," he said. "So, no, I don't think reparations are a good idea."

Coleman Hughes, who is African American, said he agreed with that sentiment saying reparations are an “insult many African Americans.”

However, Coates criticized McConnell over his comments on reparations saying: "For a century after the Civil War, black people were subjected to a relentless campaign of terror, a campaign that extended well into the lifetime of Majority leader McConnell." He added that "it is tempting to divorce this modern campaign of terror, of plunder, from enslavement. But the logic of enslavement, of white supremacy, respects no such borders."

ABC News' Briana Stewart, Miriam Khan Christen Hill and Lissette Rodriguez contributed to this report.