Judiciary

Jerrold Nadler

New York

Lifelong New Yorkers, Mr. Nadler and President Trump have been at each other’s throats since the 1990s, when Mr. Trump was a real estate developer and the Manhattan representative stood in the way of one of his West Side developments. Mr. Nadler’s objections earned him a Trumpian jab — “one of the most egregious hacks in contemporary politics” — but as the chairman of one of the most powerful committees in Congress, Mr. Nadler could bring the president serious pain and potentially oversee his impeachment.

Mr. Nadler, 71, has pledged to start investigations into potential violations of anti-corruption clauses in the Constitution, Mr. Trump’s apparent attempts to exert undue control over the F.B.I. and Justice Department, and accusations of sexual misconduct and perjury against Justice Brett M. Kavanaugh.

Mr. Nadler has said he would tread more carefully around the ongoing investigation of Mr. Trump’s campaign and Russia. In the short term, that means protecting the special counsel overseeing the inquiry, Robert S. Mueller III. But when Mr. Mueller’s work is complete, Mr. Nadler would be a key Democrat deciding whether to open an impeachment inquiry.

The committee also has jurisdiction over some of the Democrats’ highest policy priorities, including writing laws on guns, immigration policy and voting rights.