WASHINGTON (Reuters) - President Donald Trump on Sunday said disparaging comments he made about a prominent African-American lawmaker and his Baltimore district were not racist and, without citing any evidence for his claim, he called the congressman a racist.

“If racist Elijah Cummings would focus more of his energy on helping the good people of his district, and Baltimore itself, perhaps progress could be made in fixing the mess that he has helped to create over many years of incompetent leadership,” Trump said in a tweet.

Trump had attacked Cummings, a Democrat in the House of Representatives who has long been a champion for civil rights, in a series of tweets on Saturday, after the lawmaker criticized conditions at U.S. facilities housing migrants along the Mexican border.

In a post on Twitter, Trump called Cummings’ district “disgusting, rat and rodent infested.”

“No human being would want to live there,” he said.

The tweets drew pointed responses from Democrats, who said the comments were racist, a charge Trump denied on Sunday.

“There is nothing racist in stating plainly what most people already know, that Elijah Cummings has done a terrible job for the people of his district, and of Baltimore itself,” he said in a series of posts on Twitter.

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Cummings’ office did not immediately respond to a request for comment on Trump’s latest tweets. In a tweet on Saturday responding to Trump’s initial barrage, Cummings said: “Mr. President, I go home to my district daily. 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.”

Cummings is the chairman of the House Oversight Committee, which voted 23-16 along party lines on Thursday to issue subpoenas to White House officials, including Trump’s daughter Ivanka Trump and son-in-law Jared Kushner as part of a probe into possible violations of government record-keeping laws.

In an interview on CBS’s “Face the Nation,” acting White House chief of staff Mick Mulvaney said on Sunday that he understood why Trump’s comments could be perceived as racist but he said the president was speaking hyperbolically.

Trump’s remarks echoed a similar attack he made in January 2017 against another black lawmaker and icon of the civil rights movement, John Lewis. He also recently told four minority women lawmakers to “go back and help fix the totally broken and crime infested places from which they came from.”

“I absolutely think it’s important to call it out for what it is, which is racism,” Democratic presidential candidate Julian Castro told “Face the Nation.”

“There’s a pattern here,” he added. “That’s how he thinks he won in 2016 and that’s how he thinks he’s going to win in 2020.”

Cummings represents Maryland’s 7th congressional district, which according to 2010 census data was 54.6% black, had a median household income of $51,018, a figure above the median income for the nation as a whole.