Mayor Eric Adams’s successful effort to persuade the Trump administration to abandon the federal corruption indictment against him — saving him from a trial and potential prison time — was largely a political endeavor, not a legal one.

But it has nonetheless come at significant cost: The months of legal work that played out before, during and after his charm offensive won over President Trump has left him $3 million in debt.

The latest filing from his legal defense fund shows that Mr. Adams raised no money for the fund in the last three months, even as he remains on the hook for more than $700,000 per month to his lawyer, Alex Spiro, and Mr. Spiro’s firm, Quinn Emanuel, and has promised to pay his other criminal defense counsel at WilmerHale as much as $400,000 a month.

Donors had given more than $1.8 million to the fund since its creation in November 2023, with contributions coming from an influential consortium that included real estate leaders and former Mayor Michael R. Bloomberg. The City Council approved a bill in 2019 to allow elected officials to create specific funds, separate from their campaign accounts, to pay for defense lawyers.

But donations to Mr. Adams’s re-election and legal defense funds have dramatically declined, as has his political viability and popularity. Only 20 percent of voters approved of Mr. Adams’s job performance — a record low — according to a poll by Quinnipiac University last month.

Todd Shapiro, a spokesman for the mayor’s campaign, said that Mr. Adams was exploring all appropriate avenues to address the debt and would do so “in a transparent and ethical manner.”