An ethnically diverse field of candidates will vie Tuesday to replace Rep. Charles Rangel (D-Manhattan), reflective of a district that has undergone a demographic shift since the so-called Lion of Harlem took office in 1971.

Rangel, a Democratic icon of black politics who weathered countless civil rights battles as well as censure in 2010 over ethical violations, is set to retire in December.

The nine people looking to succeed him in the Democratic primary are — like the communities that make up the 13th Congressional District in upper Manhattan and the Bronx — African-American, white, Puerto Rican and Dominican.

Many have legislative chops by way of Albany.

Several said at a Bronx debate earlier this week that they would fight gridlock and corruption in Washington, D.C. while focusing at home on reforming a criminal justice system that disproportionately affects young men of color and rebuilding the dwindling stock of affordable housing.

Harlem, the cradle of black culture and politics where Rangel built his legacy, has been hard hit by gentrification.

“I’ve been a warrior against gentrification,” said Keith Wright, a 23-year member of the state Assembly and son of a prominent state Supreme Court judge. Rangel has endorsed Wright.

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Adam Clayton Powell IV, a former state assemblyman and son of the civil rights leader for which a state office building and boulevard in Harlem are named, said he’d be the “first one standing in front of the bulldozer” to stop the construction of luxury buildings without an affordable component.

State Sen. Adriano Espaillat, who failed in his 2012 and 2014 bids to unseat Rangel, assailed Wright as a “party boss.” But he said he agreed with Rangel on a signature cause: a universal draft.

“This should not be a poor people’s war,” Espaillat said. “We should have an open draft so the sons and daughters of rich people, middle-class people and poor people all go out to defend our nation.”

There also were pledges at the event Monday to unify.

“The issues facing this district are not black, they’re not white, they’re not Latino,” state Assemb. Guillermo Linares said. “They are disenfranchised communities that have no voice.”

One candidate whose experience has been rooted more in Washington, D.C. than Albany is Clyde Williams, formerly national political director of the Democratic National Committee and an adviser to President Bill Clinton after he left the White House.

“We have the ability to turn the page on the politics of old,” Williams said, “ . . . the politics that have brought us corruption, incompetence and mismanagement.”

Also running are Suzan Johnson Cook, a small business owner who served as a New York Police Department chaplain; Michael Gallagher, a former systems analyst who is a stay-at-home dad; Sam Sloan, an elite chess player; and Yohanny Caceres, who works at an insurance brokerage.