Of all the offices she has sought — Ms. Teachout also ran for Congress in the 19th District, upstate, two years ago, losing in a tight race to the Republican John Faso — the office of attorney general is closest to her experience. A specialist in antitrust law and corruption, she has been advising the attorneys general in Washington and Maryland in their emoluments lawsuit against Donald Trump. On July 25, the federal judge overseeing the case ruled that it could go forward and cited Ms. Teachout’s work in the opinion.

From the moment that Mr. Trump became president, Ms. Teachout has been talking about the possibility — in her mind, the absolute certainty — that his financial involvements with foreign state-controlled companies are in violation of the emoluments clause of the Constitution, which prohibits public servants from accepting anything of significant value from a foreign power without the clear consent of Congress. Seventy-two hours after Mr. Trump became president, she and other lawyers filed a federal lawsuit against him on these grounds.

Before Mr. Schneiderman’s fall, Ms. Teachout had twice pushed him to go after the president on emoluments, she told me in her campaign headquarters in East Harlem one afternoon. He didn’t do it. Of all the candidates running for attorney general in the Democratic field — they include New York City public advocate Letitia James, who has the governor’s endorsement and the backing of the state party apparatus; Congressman Sean Patrick Maloney; and Leecia Eve, an upstate lawyer and former adviser to Hillary Clinton — Ms. Teachout is running the loudest, most aggressive campaign. She also has 120 active volunteers absorbed from Alexandria Ocasio-Cortez’s blockbuster primary campaign.

Several days ago, in response to a report in The New Yorker magazine about sexual harassment at CBS, Ms. Teachout stood outside the network’s headquarters and talked about how, if elected, she would investigate companies within her jurisdiction and hold them accountable for failures to protect victims of sexual harassment. “Time’s Up means going after institutions,” she said. She was distressed that the network’s chairman, Les Moonves, had not been suspended. “You can’t uncover the truth when people are scared of retaliation.”

As she did when she ran for governor, she is focused on corruption in Albany, on the ways that it has played out in the lives of ordinary people, driving inequality, and now she is emphasizing the links between that culture of corruption and the sexual harassment that has plagued the state capital.