After six weeks in office, President Trump has not disclosed the names of the donors who paid for his transition planning, despite a public pledge to do so.

Preparing to take power and fill thousands of federal jobs is a monthslong project that can cost tens of millions of dollars. Previous presidents, including Mr. Trump himself in 2017, used private contributions as well as federal money to foot the bill.

Those presidents made public the names of donors and their contributions within 30 days of taking office, as required under agreements they had signed with the departing administration.

The agreements offered the transition teams millions of dollars in federal funding and a variety of services, such as security, office space and the use of government servers, in exchange for following strict rules on fund-raising, including the disclosure obligation.

Mr. Trump’s 2024 transition team declined to sign such an agreement, stating in late November that it wanted to “save taxpayers’ hard-earned money” by forgoing federal support and financing its operations privately. At the same time, it promised that “donors to the transition will be disclosed to the public” and volunteered that it would “not accept foreign donations.” It did not state whether it would limit individual contributions to $5,000, as previous administrations had.

No disclosures about that financing have been made by the Trump transition, and neither it nor administration officials have given indications of a timeline for releasing that information.

Karoline Leavitt, the White House press secretary, did not respond to requests for comment.

The leaders of the Trump transition were Howard Lutnick, now the commerce secretary, and Linda McMahon, who was confirmed Monday as the education secretary. Neither Mr. Lutnick nor Ms. McMahon responded to requests for comment.

A spokesperson for the General Services Administration, which works closely with presidential transitions, said in a statement that the “the Trump-Vance Transition Team is not required to publicly disclose transition-related donations since they did not accept the services and funds outlined in” the memorandum of understanding that the agency offered the transition last fall.

Experts on government accountability noted that without a public accounting of donors, it was exceedingly difficult to know whether individuals or corporations had tried to buy influence with the new administration behind closed doors.

“Transparency on the question of private interests influencing public power is really fundamental to the health of our system, and we’re seeing that break down in very big ways,” said Max Stier, the president of the Partnership for Public Service, a nonpartisan nonprofit that promotes best practices in the federal government. “They made a promise. They owe it to the public to fulfill that.”

Mr. Trump’s previous transition, after the 2016 election, had roughly 120 employees, used government office space and email servers and received $2.4 million in federal funds. In exchange, it disclosed that more than 3,000 people, companies and advocacy organizations donated $6.5 million to the effort, with those contributions capped at $5,000 apiece, as required by the G.S.A. agreement.

Far less is known about the financing of the most recent Trump transition. Operating largely out of private offices in West Palm Beach, Fla., and eschewing government servers, the transition appears to have heavily involved the billionaire Elon Musk — who spent at least $288 million to help elect Mr. Trump and now leads the so-called Department of Government Efficiency — as well as a number of other technology industry executives.

Trump Vance 2025 Transition Inc., as the transition is formally known, was registered in Florida as a “dark money” nonprofit that does not have to disclose its donors to the Internal Revenue Service. The funds cannot be used to enrich the transition’s officers, but they can be directed to support political candidates or to pay Mr. Trump’s businesses for services provided.

Mr. Trump’s post-election fund-raising was not limited to the transition. His inaugural committee, which is a separate entity, brought in more than $170 million in private donations as of early January, a record.

Unlike the transition, the inaugural committee is legally required to report donations to the Federal Election Commission. Although the inaugural committee has not yet filed a report with that regulator, a number of high-profile donors have revealed their contributions. Many of those entities have government contracts or are engaged in legal cases involving federal agencies.

Among them are the technology companies Amazon, Meta, Google and Microsoft, each of which donated $1 million. Kraken, a cryptocurrency exchange that was sued by the Securities and Exchange Commission in 2023, put in $1 million as well. On Monday, the S.E.C. said it was dropping the case voluntarily. Last week, it dismissed a suit against another cryptocurrency exchange, Coinbase, which also donated $1 million to Mr. Trump’s inauguration.

David A. Fahrenthold contributed reporting.