Hakeem Jeffries, poised to succeed Nancy Pelosi, would make history.

Representative Hakeem Jeffries, the New Yorker poised to succeed Speaker Nancy Pelosi as the leader of House Democrats, is a political liberal, a former corporate lawyer and an exceedingly careful tactician who rose to the pinnacle of power representing some of the nation’s most iconic Black neighborhoods.

If Mr. Jeffries secures his ascent in the coming weeks, he would become the first new House Democratic leader in two decades and make history: No Black politician has ever led a House or Senate caucus for either party.

His elevation would also further consolidate power in his home borough of Brooklyn, where Mr. Jeffries represents a plurality Black district and lives less than a mile from the Senate Democratic leader, Chuck Schumer.

Mr. Jeffries, 52, currently House Democrats’ fifth-ranking leader, helped craft the messaging plan, heavy on pocketbook issues like health care and taxes, that Democrats used to reclaim the majority in 2018. He was a vehement critic of former President Donald J. Trump, whom he once called the “grand wizard of 1600 Pennsylvania Avenue,” in a reference to the Ku Klux Klan. He was also appointed, by Ms. Pelosi, as one of the House prosecutors during Mr. Trump’s first impeachment trial. (He quoted from Biggie Smalls, a fellow Brooklynite, during the trial.)

In many ways, he and Ms. Pelosi have little in common.

The daughter of a congressman and former mayor, she commands vast personal wealth and came to embody the progressive social politics of her adopted hometown, San Francisco, in stilettos. She is a master legislator who has helped pass landmark legislation for two decades.

He is the son of a middle-class social worker and case worker for New York City who still lives in the heart of Black Brooklyn and often pairs his suits with sneakers. Outside of bipartisan federal sentencing reform, his own legislative record is relatively thin.

But they do share key qualities. Both enjoy the widespread confidence of colleagues, have shown a willingness to check the most aggressive left-leaning factions of their party, and have earned reputations as disciplined messengers.

Without ever declaring his desire for the top job, Mr. Jeffries appears to have more or less cleared the field of potential competition in recent months. On Thursday, he declined to publicly discuss his future, repeatedly directing attention back to Ms. Pelosi, whom he called “a leader for the ages.”

“We’ll see what happens as we move forward,” he told reporters in the Capitol. “But now is the moment to celebrate.”

Before winning a seat in Congress in 2012, Mr. Jeffries served for six years in the New York State Assembly. He has also been a corporate lawyer for CBS and Paul, Weiss, and once considered running for mayor of New York City.

Mr. Jeffries is married to a social worker and has two sons.

Emily Cochrane contributed reporting.