National Guard troops were poised to deploy in Washington on Tuesday evening as President Trump’s plan to use the federal government to crack down on crime in the city began to take shape.

Mr. Trump on Monday described the nation’s capital in apocalyptic terms as a crime-infested wasteland — a description that ignores the extent to which crime has been falling in the city over the last two years. But it remains unclear whether the eventual show of force will match the president’s rhetoric.

“This is only the beginning,” Karoline Leavitt, the White House press secretary, said Tuesday. “Over the course of the next month, the Trump administration will relentlessly pursue and arrest every violent criminal in the District who breaks the law, undermines public safety and endangers law-abiding Americans.”

Ms. Leavitt boasted that a federal task force, which includes some local officers, made 23 arrests on Monday evening in connection with a range of crimes. In Washington, a city of roughly 700,000 people, the Metropolitan Police Department makes an average of 68 arrests a day, officials said.

A White House official, speaking on the condition of anonymity to discuss operational details, said National Guard troops were expected to begin patrolling the streets of Washington by Tuesday night, although city officials said the troops would not have the authority to make arrests.

Muriel Bowser, the mayor of Washington, and Pamela A. Smith, her police chief, met Tuesday morning with Attorney General Pam Bondi, and the city officials emerged from the meeting saying they were focused on how to make the most of the federal support. Ms. Bowser said she wanted to make sure the federal force was “being well used, and all in an effort to drive down crime.”