WASHINGTON — Upping a feud with an influential black lawmaker, U.S. President Donald Trump on Sunday assailed Rep. Elijah Cummings as a “racist” over the “rodent-infested mess” in his district while White House aides sought to downplay his comments as frustration over Democrats’ unrelenting investigations.

In a series of tweets, Trump insisted that his comments Saturday referring to Cummings’ majority-black district as a disgusting mess where “no human being would want to live” were not racist. On the contrary, Trump argued, “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.”

“His radical ‘oversight’ is a joke!” Trump added.

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His comments capped a weekend of attacks on Cummings, the powerful chairman of the House Oversight and Reform Committee, and marked the latest rhetorical shot against non-white lawmakers that have exacerbated racial tensions. Two weeks ago, Trump caused a nationwide uproar with racist tweets directed at four Democratic congresswomen of color as he looked to stoke racial divisions for political gain heading into the 2020 election.

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. His radical “oversight” is a joke! — Donald J. Trump (@realDonaldTrump) July 28, 2019

A White House aide said Sunday that Trump, frustrated by the Democrats’ unrelenting investigations and talk of impeachment, swung hard at Cummings and his Baltimore district because he believes such Capitol Hill critics are neglecting serious problems back home in their zeal to undermine his presidency.

Acting chief of staff Mick Mulvaney insisted in two national television interviews that that Trump was not making racist comments. Mulvaney, a former congressman himself, said he understood why some people could perceive Trump’s words as racist.

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Mulvaney said Trump’s words were exaggerated for effect — “Does the president speak hyperbolically? Absolutely” — and meant to draw attention to Democratic-backed investigations of the Republican president and his team in Washington.

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“Instead of helping people back home, they’re focusing on scandal in Washington D.C., which is the exact opposite of what they said they would do when they ran for election in 2018,” Mulvaney said, pointing at Democrats who now control the House.

He asserted that Trump’s barbs were a reaction to what the president considered to be inaccurate statements by Cummings about conditions in which children are being held in detention at the U.S.-Mexico border.

At a hearing last week, Cummings accused a top administration official of wrongly calling reports of filthy, overcrowded border facilities “unsubstantiated.”

“When the president hears lies like that, he’s going to fight back,” Mulvaney said.

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Trump’s tweets Saturday also charged that Cummings’ district, which includes Johns Hopkins Hospital, the Social Security Administration and the national headquarters of the NAACP, is “considered the worst run and most dangerous anywhere in the United States.”

Condemnation followed from Democrats over the weekend, including some of the party’s presidential candidates. Statements from a spokesman for Maryland’s Republican governor and from the lieutenant governor defended Cummings’ district and its people.

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Trump, unbowed, resumed the verbal volleying 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. Dems always play the race card when they are unable to win with facts. Shame!”

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The president has tried to put racial polarization at the centre of his appeal to his base of voters, tapping into anxieties about demographic and cultural changes in the nation in the belief that the divided country he leads will simply choose sides over issues such as race.

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Mulvaney argued that Trump would criticize any lawmaker, no matter the person’s race, in a similar way if Trump felt that individual spoke unfairly about the president’s policies. He volunteered that if Rep. Adam Schiff, the California Democrat who leads the House Intelligence Committee, had made the same remarks as Cummings, Trump would have pushed back.

“It has zero to do with the fact that Adam is Jewish and everything to do with Adam would just be wrong if he were saying that,” Mulvaney said. “This is what the president does. He fights and he’s not wrong to do so.”

To Mulvaney, Trump was “right to raise” the challenges faced in Cummings’ district at the same time that Cummings and other Democrats are “chasing down” the Russia investigation undertaken by Robert Mueller and pursuing “this bizarre impeachment crusade.”

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Nonetheless, the chief of staff said he understood why some people view Trump’s comments as racist, “but that doesn’t mean that it is racist.”

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“The president is pushing back against what he sees is wrong,” he added. “It’s how he’s done it in the past and he’ll continue to do it in the future.”

Cummings is leading multiple investigations of the president’s governmental dealings. In his direct response to Trump on Twitter, 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 has also drawn the president’s ire for investigations touching on his family members serving in the White House. His committee voted along party lines Thursday to authorize subpoenas for personal emails and texts used for official business by top White House aides, including Ivanka Trump and her husband, Jared Kushner.

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Democratic presidential candidate Julián Castro said Trump was engaging in “racial priming.”

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“Using this language and taking actions to try and get people to move into their camps by racial and ethnic identity. That’s how he thinks he won in 2016 and that’s how he thinks he’s going to win in 2020,” Castro said.

Earlier this month, Trump drew bipartisan condemnation following his call for Democratic Reps. Ilhan Omar of Minnesota, Alexandria Ocasio-Cortez of New York, Ayanna Pressley of Massachusetts and Rashida Tlaib of Michigan to get out of the U.S. “right now.” He said that if the lawmakers “hate our country,” they can go back to their “broken and crime-infested” countries.

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. — Elijah E. Cummings (@RepCummings) July 27, 2019

All four lawmakers of colour are American citizens and three of the four were born in the U.S. The House later voted largely along party lines to condemn his “racist comments.”

Mulvaney claimed that if he had focused on investigations when he was in Congress rather than poverty and other issues, “I’d get fired.”

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More rural than Cummings’ district, Mulvaney’s former district in South Carolina has a lower per-capita income than the one targeted by Trump, and the poverty rates are roughly the same.

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Cummings’ district is about 55 per cent black and includes a large portion of Baltimore. The city has struggled with violent crime, with more than 300 homicides for four years in a row. It has crumbling infrastructure and a police department under federal oversight.

Mulvaney was interviewed on Fox News Sunday and CBS’ Face the Nation, where Castro also appeared.