After scrutinising the request for more than an hour, Manhattan federal Judge Dale E Ho declined to rule immediately, saying he wanted to carefully review the "unusual situation".
But, acknowledging the vast political and legal implications, which include Adams' pending re-election campaign and looming April 21 trial date, he indicated he would make a decision soon.
"I'm not going to shoot from the hip right here on the bench," Ho said on Wednesday.
But, he noted, "it is not in anyone's interest for this to drag on".
The Justice Department's request - lodged by officials in Washington over the objections of federal prosecutors in Manhattan - was predicated on arguments that the case was impeding Adams' ability to govern and costing the Trump administration his co-operation in its ongoing immigration crackdown.
Acting Deputy US Attorney-General Emil Bove told Ho the Justice Department was exercising "prosecutorial discretion" and granting the request was the judge's only option.
Adams' lawyer, Alex Spiro, said no appeals court had ever sided with a judge who rejected an unopposed motion to dismiss a criminal case.
Bove urged Ho to ignore outside voices, including those of prosecutors who resigned in protest rather that go along with his demand to drop the case.
Bove said the judge should reject such claims that there was a "quid pro quo" between Adams and the Justice Department.
Adams, questioned under oath by Ho, testified there was no "other agreement" between himself and the government.
Ho also questioned Adams about a provision in the Justice Department's dismissal motion that would allow prosecutors to revive charges against him at a later date.
"I have not committed a crime," Adams said. "I'm not afraid of that."
Ho scheduled the hearing after three Trump administration lawyers, including Bove, made the dismissal request on Friday.
Manhattan's top federal prosecutor resigned after she refused an order to seek dismissal.
Adams pleaded not guilty last September to charges he accepted more than $US100,000 ($A158,000) in illegal campaign contributions and lavish travel perks from a Turkish official and business leaders seeking to buy Adams' influence while he was Brooklyn borough president.
He faces multiple challengers in the Democratic primary in June.
Closely watching the judicial proceedings is Democratic Governor Kathy Hochul, who is considering whether to remove Adams from office amid concerns that he reached a deal to have the case dropped in exchange for the mayor's political fealty to Trump.
