Updated at 2:50 p.m.: Revised to include Cornyn remarks.

WASHINGTON — Beto O'Rourke, who caught flak in last year's Senate race for depicting police as part of a new Jim Crow era, reiterated much the same point Wednesday at a gathering of African-American activists, arguing that racial minorities are still treated more harshly in the United States.

He also vowed to create a commission to study reparations for descendants of slaves, a stance that went over well at a conference led by the Rev. Al Sharpton. The issue has emerged as a litmus test for 2020 Democratic presidential contenders.

"Absolutely I would sign that into law," O'Rourke said when Sharpton asked if he would support a reparations commission bill from Rep. Sheila Jackson Lee, D-Houston.

Fellow Texan Julián Castro went further, calling reparations long overdue.

"There are many things that we need to do in this country that have been a long time in coming, and one of those is to move forward with reparations," he said, adding, "Our country will never truly heal until we address the original sin of slavery. ... If under our Constitution we compensate people if we take their property, why wouldn't we compensate people who were considered property?"

Sharpton's National Action Network conference in New York City will attract most of the 2020 Democratic field this week.

1 / 3The Rev. Al Sharpton looks on as entrepreneur and Democratic presidential candidate Andrew Yang speaks at the National Action Network's annual convention in New York City. A dozen 2020 Democratic presidential candidates will speak at the organization's convention this week.(Drew Angerer / Getty Images) 2 / 3Rev. Al Sharpton speaks during a gathering of the National Action Network in New York.(Don Emmert / Getty Images) 3 / 3Democratic presidential candidate Julian Castro embraces the Rev. Al Sharpton during a gathering of the National Action Network in New York City.(Don Emmert / Getty Images)

Sen. John Cornyn, a Republican who may face Castro's brother, Rep. Joaquin Castro, next year, rejected the idea of reparations.

"There is no question that slavery is a scar on our history and a terrible, well, you could call it a sin that America engaged in back at our country's founding," he told Texas reporters on a weekly call. "But we've come a long, long way, obviously. And I don't see the fundamental fairness in having taxpayers today pay for mistakes that were committed 200 years ago. This strikes me more as a way to try to appeal to the energized base of the Democratic Party rather than a serious effort to deal with racial inequality or the legacy of slavery."

In New York, O'Rourke recalled conversations with Bryan Stevenson, a lawyer and activist in Montgomery, Ala., and recipient of the MacArthur Foundation "genius" prize, and creator of a memorial for more than 4,000 lynching victims in the South from 1877 to 1950.

"He said foundational to reparations is the word repair," O'Rourke said, "and foundational to 'repair' is the truth. And until all Americans understand that civil rights are not just those victories [of recent decades] but the injustices that have been visited and continue to be visited on people, we will never get the change that we need to live up to the promise of this country."

Castro, too, supports the Jackson Lee bill on reparations. The former housing secretary and San Antonio mayor also embraces the idea of a truth and reconciliation commission of the sort created in post-apartheid South Africa.

Entrepreneur Andrew Yang also spoke at the so-called Al Sharpton primary Wednesday. Most other contenders will speak Friday, including Sens. Bernie Sanders, Kamala Harris, Elizabeth Warren, Cory Booker, Kirsten Gillibrand and Amy Klobuchar; Pete Buttigieg, mayor of South Bend, Ind.; and Rep. John Delaney of Maryland.

On the issue of policing, Sharpton asked O'Rourke about police brutality and bias. The former three-term El Paso congressman argued that while individual misdeeds must be addressed, he sees inherent bias in law enforcement.

He did not invoke the term "Jim Crow," as he did in the Texas Senate race, speaking at Prairie View A&M University, a historically black school, in September. He was discussing institutial inequality — racial profiling, discriminatory stop-and-frisk searches, racially motivated police shootings and discriminatory sentencing — and said they were aptly described as the "new Jim Crow."

Sen. Ted Cruz cited the remark to depict his challenger as hostile to police for the remainder of the Senate contest.

"We support our police officers and our sheriff's deputies. We know that they have an incredibly difficult job," O'Rourke said Wednesday in New York. "They are one part of a larger system — not just of criminal justice in this country. But a system that has successfully suppressed some Americans based on their race for as long as we have been a country."

The National Action Network, he said, had shown in New York City that whites are far less likely to face run-ins with police for marijuana, even though usage rates aren't much different.

"Only some Americans likely to be of color would be stopped and frisked, to be found for possession, go behind bars and endure the consequences. The other Americans would not," he said. "So yes, there must be accountability for the enforcement of the law. There must be accountability for use of force, and federal funds to local police departments and sheriff's departments must be tied to accountability, full transparent reporting for use of force, and justice for those who use force illegally against those citizens whom they are sworn to serve and protect."

Washington correspondent Tom Benning contributed to this report.