Donald Trump attacked Al Sharpton as a “con man” who “hates whites & cops” shortly before the MSNBC host and civil rights activist is scheduled to hold a press conference Monday to criticize the president’s recent remarks about Baltimore.

“Al Sharpton would always ask me to go to his events,” Trump wrote in early morning tweets. “He would say, ‘it’s a personal favor to me.’ Seldom, but sometimes, I would go. It was fine. He came to my office in T.T. during the presidential campaign to apologize for the way he was talking about me. Just a conman at work!”

Sharpton will be joined at the event on Monday by Michael Steele, former chairman of the Republican National Committee. Both men are coming to the defense of House Oversight Committee Chairman Elijah Cummings, after the president has attacked the lawmaker and the Baltimore district he represents as “disgusting, rat and rodent infested mess.” Trump’s language has been criticized as racist — Cummings, is a prominent African-American legislator, and his district is predominantly African-American.

Trump continued with the racially charged attacks on Monday in his tweets about Sharpton.

“I have known Al for 25 years,” he wrote. “Went to fights with him & Don King, always got along well. He ‘loved Trump!’ He would ask me for favors often. Al is a con man, a troublemaker, always looking for a score. Just doing his thing. Must have intimidated Comcast/NBC. Hates Whites & Cops!”

Sharpton responded with his own tweet, attaching a picture of Trump talking to him as well as to Jesse Jackson and James Brown in 2006. In it, Sharpton says, Trump was telling him “why he respects my work. Different tune now.”

Sharpton has been an MSNBC host since 2011. His weekly program “PoliticsNation” airs Sundays.