In her letter, Ms. Hardy cited exemptions to the Freedom of Information Act for correspondence involving the president’s staff and internal policy deliberations, suggesting that the disclosure of this material would “inhibit the frank and candid exchange of views that is necessary for effective government decision-making.”

David McCraw, a lawyer for The Times, said the newspaper would challenge the blanket withholding of the documents and would ask the judge overseeing the lawsuit, Judge Amy Berman Jackson, to approve an expedited schedule for briefs and arguments given the urgent public interest in learning more about the dispute.

The heart of the accusation against Mr. Trump is that he abused his official powers, including withholding a promised White House meeting and congressionally mandated military aid, in an attempt to coerce Ukraine’s president into announcing investigations that could deliver personal political benefits to Mr. Trump.