Elijah Cummings, head of U.S. House oversight panel probing Trump, has died

(SOUND BITE) U.S. REPRESENTATIVE ELIJAH CUMMINGS, SAYING:

"We are the United States of America. We are the greatest country in the world."

U.S. Representative Elijah Cummings, one of the most powerful Democrats in Congress, died at age 68 Thursday morning.

In a statement, his office said he "passed away at John Hopkins Hospital due to complications concerning longstanding health challenges."

Cummings did not return to Congress this week after reportedly undergoing an unspecified medical procedure.

He had heart surgery in 2017, and had been using a walker in recent months.

(SOUND BITE) U.S. REPRESENTATIVE ELIJAH CUMMINGS, SAYING:

"We all should be able to agree..."

Cummings, a champion of civil rights issues, was a trial lawyer before being elected to office in 1996 to represent Baltimore - his hometown.

He served as chair of the House Oversight and Reform Committee and was a key figure in the impeachment investigation of President Donald Trump.

(SOUND BITE) U.S. PRESIDENT DONALD TRUMP, SAYING:

"Those people are living in Hell in Baltimore."

Over this past summer, Trump and Cummings were involved in a feud after the president said Baltimore was "rat and rodent infested."

(SOUND BITE) U.S. REPRESENTATIVE ELIJAH CUMMINGS, SAYING:

"Do not just criticize us, but come to Baltimore and I promise you will be welcome."

Along with the impeachment probe over Trump's handling of Ukraine, the committee Cummings chaired also demanded documents related to the president's personal finances as well as possible abuses in federal agencies in the Trump administration.

(SOUND BITE) U.S. REPRESENTATIVE ELIJAH CUMMINGS, SAYING:

"None of us would have our children in that position."

The Maryland Democrat delivered an impassioned speech this summer opposing the Trump's administration's child separation policy at the U.S. southern border.

(SOUND BITE) U.S. REPRESENTATIVE ELIJAH CUMMINGS, SAYING:

"We're better than that. And I don't want us to lose sight of that. When we are dancing with the angels, these children will be dealing the issues that have been presented to them."

Cummings is survived by his wife and three children.