"You know, it's sort of like if you have a patient who has cancer," Carson said of Baltimore. "You can dress them up and put a nice suit on them, and you can try to ignore it. But that cancer is going to have a devastating effect. You have to be willing to address that issue if you're ever going to solve it."
Carson's press conference in west Baltimore at the back of a local housing project came days after Trump called Baltimore a "disgusting, rat and rodent infested mess" and accused Maryland Democratic Rep. Elijah Cummings' district of stealing or wasting "billions of dollars" -- attacks Democrats have said is part of a long-running pattern of racism for the president.
Carson – who lived in Baltimore for 36 years working as a surgeon at Johns Hopkins Hospital and whose son has worked as a developer in Baltimore – said he wished Trump would "express his heart to the people the way he has expressed it to me."
On Tuesday, Trump shrugged off allegations of racism, insisting the term was "overused."
"Everyone is called a racist now," Trump told C-SPAN in an interview.
When it comes to problems in the city, local officials point to landlords, including Trump's son-in-law Jared Kushner, whose family real estate firm owns apartments and townhomes in Baltimore. In 2017, the county reported some 200 code violations in apartments owned by the Kushner family in one year alone.
In his remarks, Carson did not address those allegations, insisting instead that Baltimore has already received billions in federal money and that federal aid wasn't the problem.
"We have some threats but it's not China. It's not Russia, it's not North Korea. It's us, and whether we can work together and realize we are not each other's enemies," Carson said. The president, he later added, is "very willing to work with people here in Baltimore, including with Elijah Cummings," Carson said.
Carson invited Cummings to attend the Wednesday press conference with a few hours' notice. Cummings said he couldn't join due to "scheduling commitments" and did not comment on Carson's remarks.
Trump had attacked Cummings on Twitter after the Democrat, as chairman of the House Oversight and Government Reform Committee, sharply criticized the administration's handling of the border crisis and allegations of misconduct and child neglect by U.S. Border Patrol agents.
"As proven last week during a Congressional tour, the Border is clean, efficient & well run, just very crowded," Trump tweeted.
He added, Cummings' "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 via Twitter noting that he returns home to his district daily.
"Each morning, I wake up, and I go and fight for my neighbors," the Maryland Democrat wrote. "It is my constitutional duty to conduct oversight of the Executive Branch. But, it is my moral duty to fight for my constituents."
Cummings' committee announced Wednesday that the panel was demanding documents from the U.S. Customs and Border Protection (CBP) related to its internal investigation into a private Facebook group that included offensive posts from active-duty border agents.
Cummings wrote in a letter to CBP that the panel was concerned that some of the agents responsible for the posts "may still be working with immigrants and children."
ABC producer Matt Seyler contributed to this report.