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Letitia James, the incoming New York attorney general, has made no secret of how she feels about President Trump.
She calls him an “illegitimate president.” She says her decision to run for attorney general was largely “about that man in the White House who can’t go a day without threatening our fundamental rights.”
She has suggested that Mr. Trump could be charged with obstruction of justice, and implied that foreign governments channeled money to Mr. Trump’s family’s real estate holdings, which she characterized as a “pattern and practice of money laundering.”
Democratic attorneys general across the country, including Ms. James’s predecessors in New York, have repeatedly used their offices to confront Mr. Trump. But since her election, Ms. James has opened herself up to criticism that she has gone too far in allowing politics to shape her agenda.
Her strident attacks on the president could potentially threaten the legal standing of cases that her office brings against Mr. Trump, his family members or their business interests, legal experts said.
Mr. Trump recently accused Ms. James of winning her election on a “GET TRUMP agenda,” and of doing “little else but rant, rave & politic against me.”
Ms. James has signaled that she will be as aggressive as New York’s current attorney general, Barbara D. Underwood, and her predecessor, Eric T. Schneiderman, both Democrats, in pursuing Mr. Trump in his home state.
She will continue a lawsuit against the Trump Foundation that was filed by Ms. Underwood and may also examine whether Mr. Trump is in violation of the Constitution’s emoluments clause, which bars federal officials from accepting gifts, or emoluments, from foreign powers without congressional approval.
After an investigation by The New York Times showed that Mr. Trump received hundreds of millions of dollars from his parents, most of it by helping them dodge taxes, Ms. James issued a statement calling for “a full examination of these claims” by the state, including the attorney general’s office.
“Donald Trump’s days of defrauding Americans are coming to an end,” Ms. James said.
Daniel S. Goldman, a fellow at the Brennan Center for Justice and a former assistant United States attorney in Manhattan, said that it was unlikely that Ms. James’s remarks could directly lead to a dismissal of charges against Mr. Trump, but that they could put cases in jeopardy because of an appearance of “an individualized political vendetta.”
“If there were to be a motion to dismiss because of bias, the attorney general’s office would have to show a stronger factual basis for the legal issue,” Mr. Goldman said. “If there is a close call along the way, it could have an impact on the way a judge rules.”
A similar issue arose in 2015 when Judge Valerie E. Caproni of Federal District Court in Manhattan chided Preet Bharara for publicly criticizing Sheldon Silver, the former New York Assembly speaker, after he was charged with corruption. Mr. Bharara, then the United States attorney in Manhattan, had suggested to reporters that Mr. Silver had “sold his office to line his pockets.”
Mr. Silver asked for the charges to be dismissed. Judge Caproni declined, but said she was “troubled” that Mr. Bharara’s remarks appeared to “bundle together unproven allegations” about Mr. Silver. She warned his office to try the case “in the courtroom and not in the press.”
Mr. Goldman characterized Mr. Trump’s criticism of Ms. James as the right message from the wrong messenger, given how Mr. Trump has used public remarks on Twitter to discredit criminal and civil investigations involving himself, his family and associates.
“Donald Trump is desperately trying to turn everything into a hyperpartisan issue, including criminal justice,” Mr. Goldman said. “It’s essential that prosecutors maintain their neutrality and an objective view of the facts and the evidence, no matter the politics involved.”
In an interview, Ms. James defended her remarks about the president, adding that she believed that her race and gender were shaping what she characterized as assumptions and misconceptions about how she would perform as attorney general.
Ms. James is the first woman in New York to be elected as attorney general, the first African-American woman to be elected to statewide office, and the first African-American to serve as attorney general. Before winning election, she was the New York City public advocate.
“This is similar to when I was about to take office as public advocate, and individuals expressed concerns,” Ms. James said. “What I have done repeatedly throughout my life is I have been underestimated and have continued to perform.”
Ms. James’s role could take on heightened significance should Mr. Trump decide to issue pardons for anyone implicated in the investigation by the special counsel, Robert S. Mueller III, into Russian meddling in the 2016 presidential election.
Convictions under state law, however, are not covered by federal pardons. Ms. James has championed a change in state law that would allow the prosecution of those who have been pardoned by the president.
The importance of Ms. James’s position was underscored when Ms. Underwood’s office announced on Dec. 18 that Mr. Trump and his lawyers had agreed to shut down the Donald J. Trump Foundation.
That agreement emerged from an investigation that began under Mr. Schneiderman, and from a lawsuit filed by Ms. Underwood.
The lawsuit, which seeks restitution and penalties and could result in Mr. Trump and his three oldest children being barred from the boards of other New York charities, will proceed under Ms. James’s watch.
Mr. Trump’s lawyers had argued that the case should be dismissed because it was politically motivated. A state judge ruled in November that the case could proceed.
Ms. James began her legal career as a lawyer at the Legal Aid Society, eventually becoming head of the New York attorney general’s Brooklyn regional office. In 2003, she was elected to the New York City Council; she was elected as the New York City public advocate a decade later.
As public advocate, Ms. James sought to redefine the position: She filed 12 lawsuits on behalf of city residents, more than all of her predecessors combined, but to mixed results. A small handful of cases were thrown out because judges ruled that she lacked standing to file the lawsuits.
Even inside the attorney general’s office, some shared concerns that Ms. James’s outspoken approach toward Mr. Trump may undermine her efforts.
Eric Soufer, who served as senior counsel for policy for Mr. Schneiderman, said Ms. James’s bluntness had caused “apprehension and uneasiness” among some high-level officials who have left the office after her election.
“You’ve got to let the cases do the talking,” said Mr. Soufer, now a managing director at Tusk Strategies, a political consulting group. “She doesn’t need to expose what she thinks about Donald Trump. What people want are results.”
Ms. James acknowledged that her words and promises would carry more weight as attorney general.
“I recognize that this is the premier law office in this nation,” Ms. James said in the interview. “I recognize that as the face of this office, one must be circumspect.”
Days later, Ms. James was back in attack mode, telling NBC News that she would use “every area of the law to investigate President Trump and his business transactions and that of his family.”