Rep. Elijah E. Cummings, the son of sharecroppers who rose to represent parts of Baltimore, the city where he was born and raised, died early Thursday at age 68.

The Maryland Democrat died at Gilchrist Hospice Care, which is affiliated with Johns Hopkins Hospital, at about 2:30 a.m. EDT from "complications concerning longstanding health challenges," his office confirmed in a statement.

He underwent a medical procedure in September that had kept him from returning to work. On Sept. 30, he had told The Baltimore Sun that he expected to be back in Congress by mid-October.

Cummings, as chairman of the House Oversight Committee, had recently sparred with President Donald Trump as the 23-year veteran of Capitol Hill led multiple investigations into the president and his administration. Those investigations also involved the president's family members serving in the White House – his daughter Ivanka Trump and son-in-law Jared Kushner.

A school counselor once told Cummings that he was too slow a learner and too poor a speaker to ever fulfill his dream of becoming a lawyer. In 1996, Cummings told The Associated Press those comments left him "devastated."

"My whole life changed. I became very determined," said Cummings, who went on to become not just a lawyer, but also a judge.

Cummings was elected to the Maryland House of Delegates in 1983, where he served until 1996. In 1995, he became the first African American to serve as speaker pro tempore in the Maryland Legislature.

He was elected to the House of Representatives in a 1996 special election to fill the seat vacated when Rep. Kweisi Mfume left Congress to head the NAACP.

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His widow, Maya Rockeymoore Cummings, is chairwoman of the Maryland Democratic Party.

"Congressman Cummings was an honorable man who proudly served his district and the nation with dignity, integrity, compassion and humility," she said in a statement

"He worked until his last breath because he believed our democracy was the highest and best expression of our collective humanity and that our nation’s diversity was our promise, not our problem. It has been an honor to walk by his side on this incredible journey. I loved him deeply and will miss him dearly," she said.

House Speaker Nancy Pelosi's office announced Thursday that flags at the Capitol would be flown half-staff to honor Cummings. The speaker said America "lost a voice of unsurpassed moral clarity and truth" with Cummings' passing.

“In the House, Elijah was our North Star," she said. "He was a leader of towering character and integrity, whose stirring voice and steadfast values pushed the Congress and country to rise always to a higher purpose."

A former chairman of the Congressional Black Caucus, Cummings was outspoken on civil rights and voter access.

In 2004, he called on then-President George W. Bush to send troops to Haiti as part of an international force to restore order and protect democracy there. And he was a leading voice among the caucus members last year who called for congressional hearings to examine the fatal shootings of black people by police officers.

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In July, Trump lashed out at Cummings after the congressman criticized the administration's handling of migrant detention centers and his committee authorized subpoenas for senior White House officials' electronic communications. The president called Cummings a "brutal bully" and said Baltimore was a "rodent-infested mess" where "no human being would want to live."

"Mr. President, I go home to my district daily. Each morning, I wake up, and I go and fight for my neighbors," Cummings said in response. "It is my constitutional duty to conduct oversight of the Executive Branch. But, it is my moral duty to fight for my constituents."

He called on Trump to help the majority-black city address its problems with poverty and crime, rather than "trash" it.

'Don't just come and criticize':Elijah Cummings defends Baltimore in face of Trump's insults

Trump's remarks were condemned as racist by many, including Pelosi. The president denied being racist and called Cummings "racist" in turn.

After Trump told four minority congresswomen to "go back" to their countries of origin, Cummings told The Baltimore Sun the president's rhetoric took him back to the racial animosity he felt during the civil rights era.

“I don’t think these Republicans or Trump fully understand what it feels like to be treated like less than a dog,” Cummings said. "I’m feeling the same things that I felt when these white folks down in South Baltimore were throwing rocks and bottles at me. But now, I feel like it’s the president of the United States doing it.”

He was a passionate promoter of Democratic policies and a fierce critic of the Trump administration, but Cummings was also noted for his fair and respectful treatment of his Republican counterparts.

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For example, when Rep. Rashida Tlaib, D-Mich., appeared to accuse Rep. Mark Meadows, R-N.C., of racism during a hearing centered on Trump's former personal attorney Michael Cohen, Cummings came to Meadows' defense.

Cummings said Meadows was one of his best friends on the Oversight Committee.

"I can see and feel your pain. I feel it. And I don't think Ms. Tlaib intended to cause you that, that kind of pain and that kind of frustration," Cummings told Meadows.

In his closing remarks after Cohen's testimony, Cummings bemoaned the divisions within the country and the president's remarks attacking his former personal fixer as a "rat."

"We’re better than that! We really are. And I’m hoping that all of us can get back to this democracy that we want, and that we should be passing on our children so they can do better than what we did," Cummings said.

"When we’re dancing with the angels, the question we’ll be asked: In 2019, what did we do to make sure we kept our democracy intact? Did we stand on the sidelines and say nothing?" he asked.

Cummings in photos:Maryland congressman Elijah Cummings dies at 68

On Thursday, Trump offered his "warmest condolences" to Cummings' family and friends.

"I got to see first hand the strength, passion and wisdom of this highly respected political leader," Trump tweeted. "His work and voice on so many fronts will be very hard, if not impossible, to replace!"

Former President Barack Obama said he his wife, Michelle Obama, were "heartbroken" by Cummings' death who they said, "showed us all not only the importance of checks and balances within our democracy but also the necessity of good people stewarding it."

"Today we have lost a giant," House Majority Whip James Clyburn said in a statement mourning Cummings, a close ally in Congress whom he called a "public servant to his core."

"His dedication to fairness and his ability to navigate the choppy waters of partisanship were the hallmarks of his leadership. There will not be another leader like him," Clyburn said.

Civil rights icon Rep. John Lewis, D-Ga., said the country "lost a great leader at a time of crisis in our democracy."

Lewis pointed to Cummings' actions after an African American man died in Baltimore police custody, sparking riots.

"Even during a time of turmoil when mourners spilled into the streets during the tragic death of Freddie Gray, Rep. Cummings dove into the sea of humanity, joined the people of his district, and became a calming force at a turbulent time," Lewis said.

House Majority Leader Steny Hoyer, D-Md., said he was "shocked and saddened" by the news of Cummings' death, calling him a "man of principle, patriotism, and conviction, whose loss will be deeply felt throughout the State of Maryland and our country."

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Hoyer said he learned a lot by working with Cummings for more than 20 years, including "patience and fortitude when confronted with malice from opponents, which he answered with 'charity for all.'"

"And his faith in democracy served as a lesson to us all. When talking about the times we fell short of our Founders’ vision, Elijah would say ‘we are better than this.’ Elijah Cummings was better than most," Hoyer said.

Senate Minority Leader Charles Schumer, D-N.Y., described Cummings’ passing as “a gut punch” on MSNBC’s "Morning Joe."

“He was not just a great congressman, he was a great man,” he said. “He had a combination of being strong when he had to be, and had to be quite often, but also being kind and decent and caring and honorable.”

Former Rep. Donna Edwards, D-Md., who served with Cummings from 2008-2017, said in a tweet that "Baltimore, Maryland, and our nation have lost a true warrior for truth and justice. Rep. Elijah Cummings rests with the angels."

"The death of Chairman Cummings leaves an irreplaceable void in our hearts, in our Maryland and in our Congress," Sen. Ben Cardin, D-Md., said in a statement. "Chairman Cummings guaranteed a voice to so many who would otherwise not have one, and stood as a symbol for the heights one could reach if they paid no mind to obstacles, naysayers and hate."

Cummings' Republican colleagues also praised him and mourned his passing. "Elijah’s passion for serving his beloved city was easy to see in everything that he did, and his determination to fight for equality and civil rights will never be forgotten," Rep. Liz Cheney, R-Wyo., the chairwoman of the House Republican Conference said in a statement. "He was a friend to all and sought to use his position in Congress to bridge divides, not widen them.

Out of respect for Cummings, Rep. Matt Gaetz, R-Fla., postponed a scheduled news conference where he had planned to demand greater transparency in the ongoing impeachment inquiry.

"Many are in mourning and we hope that peace and comfort can enter the hearts of those who cared for Elijah," Gaetz said.

"Elijah Cummings was a good friend and a powerful advocate for what he believed," Sen. Roy Blunt, R-Mo., said. "He saw a lot of things change in his lifetime, but understood we weren’t where we should be yet.”

Rep. Jim Jordan, R-Ohio, the ranking Republican on the Oversight Committee, said Cummings "injected an unyielding passion and purpose into his work." He said Cummings' staff "are among the hardest working people on Capitol Hill" and that their "loyalty and affinity for him speaks volumes about his character."

Here is a look at some other reactions to Cummings' death:

Contributing: Adrianna Rodriguez and Deborah Barfield Berry, USA TODAY; The Associated Press