President Donald Trump expressed condolences on Thursday in response to the death of Rep. Elijah Cummings.

“My warmest condolences to the family and many friends of Congressman Elijah Cummings,” Trump wrote on Twitter. “I got to see first hand the strength, passion and wisdom of this highly respected political leader. His work and voice on so many fronts will be very hard, if not impossible, to replace!”

Cummings died at Johns Hopkins Hospital at 2:45 a.m. Thursday morning as a result of “complications concerning longstanding health challenges,” according to his staff.

The veteran lawmaker helped launch the impeachment effort in the House before his absence in the House in recent weeks prior to a medical procedure. As chairman of the House Oversight Committee, Cummings also launched several probes into President Trump and his family.

In July, Cummings exploded at Acting Secretary of Homeland Security Kevin K. McAleenan during a congressional hearing, accusing him of failing to take care of migrants apprehended while crossing into the United States.

Trump responded by accusing the congressman of failing the “rat and rodent-infested” city of Baltimore and his congressional district.

Cummings did not respond directly to Trump but implicitly criticized him in a follow-up speech at the National Press Club.

“Those in the highest levels of the government must stop invoking fear, using racist language, and encouraging reprehensible behavior,” Cummings said.

Trump and Cummings tried to work together in a bipartisan way to reduce drug prices in the early days of the Trump presidency. Cummings revealed in December 2017 that the president phoned the Baltimore lawmaker three times to discuss the issue.