WASHINGTON — President Trump lashed out at a leading African-American congressman Saturday, calling him “a brutal bully’’ who represents a Baltimore-based district that has become a “disgusting, rat and rodent infested mess’’ where “no human being would want to live.’’

Trump’s attack on Representative Elijah E. Cummings, a Maryland Democrat and a leading critic of the president, parroted a segment that aired earlier in the morning on “Fox & Friends.’’ The president suggested that the congressman was a hypocrite for criticizing conditions in migrant detention centers at the southwestern border when his own district is blighted. Trump also made a vague and unsubstantiated insinuation of corruption.

“Rep, Elijah Cummings has been a brutal bully, shouting and screaming at the great men & women of Border Patrol about conditions at the Southern Border, when actually his Baltimore district is FAR WORSE and more dangerous,’’ Trump wrote. “His district is considered the Worst in the USA.’’ He went on: “Cumming District is a disgusting, rat and rodent infested mess. If he spent more time in Baltimore, maybe he could help clean up this very dangerous & filthy place.’’

Cummings responded on Twitter shortly afterward, saying that he was a vigorous advocate for his district. “Mr. President, I go home to my district daily,’’ he wrote. “Each morning, I wake up, and I go and fight for my neighbors. It is my constitutional duty to conduct oversight of the Executive Branch. But, it is my moral duty to fight for my constituents.’’

The congressman pointed to a hearing he held Friday on his effort to legislate lower drug prices, which would help his Baltimore constituents. “You told me then that you supported the legislation and that you would work with me to make it happen,’’ Cummings said, still addressing the president. “I took you at your word.’’

Trump’s blasts could revive the criticism that followed his attacks on four first-term Democratic congresswomen of color, who he angrily declared should “go back’’ to their home countries, even though three of them were born in the United States and the fourth is also an American citizen. The president’s use of racist tropes generated enormous anger on the part of Democrats and some Republicans, leading the House to pass a resolution, largely along party lines, condemning his remarks.

The Twitter assault came shortly after “Fox & Friends’’ aired a segment Saturday morning assailing Cummings for focusing on migrants more than his own urban constituents. As video footage showed boarded-up houses and trash-strewn areas of Baltimore, the Fox television host said that “living conditions at the border are better than most areas in his district.’’

Cummings’s district is 53 percent African-American, according to the census, and includes much of Baltimore as well as vast suburban stretches. Baltimore has struggled with crime in recent years, recording more murders in 2017 than any other city of at least 500,000 residents — more even than New York, a vastly larger city.

Trump has denied charges that he is racist, citing in his defense the low unemployment rates for Hispanics and African-Americans on his watch, among other things. In recent days, he has also made a point of pressuring Sweden to release rapper ASAP Rocky, who was charged with assault there, saying, “Sweden has let our African American Community down in the United States.’’

Cummings, the chairman of the House Oversight and Reform Committee, has been one of the president’s most persistent critics in Congress. Only two days ago, he was authorized by his committee to subpoena work-related text and e-mails sent on personal accounts by White House officials, including Trump’s daughter and son-in-law.

The Maryland congressman has also assailed the administration’s handling of the border. At a recent hearing, Cummings confronted Kevin McAleenan, the acting secretary of homeland security, about conditions for detained migrants, sharply criticizing the secretary’s contention that his department was doing its “level best’’ to manage the situation.

“What does that mean?’’ Cummings demanded. “What does that mean when a child is sitting in their own feces, can’t take a shower? Come on, man. What is that about? None of us would have our children in that position. They are human beings.’’

In his Twitter storm Saturday, the president said Cummings was distorting the reality, saying, “the Border is clean, efficient & well run, just very crowded.’’

Trump did not explain one of his most explosive charges, that federal taxpayer money was somehow being stolen, nor did he detail what involvement he was suggesting on Cummings’s part.

“Why is so much money sent to the Elijah Cummings district when it is considered the worst run and most dangerous anywhere in the United States,’’ the president wrote. “No human being would want to live there. Where is all this money going? How much is stolen? Investigate this corrupt mess immediately!’’

White House officials did not immediately respond to requests for clarification. A spokesman for Cummings had no comment and referred to the congressman’s Twitter posts.