Elijah Cummings, the formidable US congressman who led investigations into Donald Trump, has died aged 68 due to complications from long-standing health challenges, his has office said.

As chairman of the House Oversight and Reform Committee, Cummings led multiple probes into the president’s governmental dealings and became a target of Trump’s attacks on social media.

In July, Trump describe Cummings’ district – which encompassed a large portion of Baltimore – as a “disgusting, rat and rodent infested mess” where “no human” would want to live, and later even gloated when his house was burgled. 

Cummings responded that government officials must stop making “hateful, incendiary comments” that only serve to divide and distract the nation from its real problems.

“Those in the highest levels of the government must stop invoking fear, using racist language and encouraging reprehensible behaviour,” Cummings said in a speech at the National Press Club.

Cummings, the son of a farm labourer, was a formidable orator who passionately advocated for the poor. His long career spanned decades in Maryland politics. He rose through the ranks of the Maryland House of Delegates before winning his congressional seat in a special election in 1996 to replace Kweisi Mfume, who left the seat to lead the NAACP.

Cummings continued his rise in Congress. In 2016, he was the senior Democrat on the House Benghazi Committee, which he said was “nothing more than a taxpayer-funded effort to bring harm to Hillary Clinton’s campaign” for president.

Cummings was an early supporter of Barack Obama’s presidential bid in 2008.

Throughout his career, he used his fiery voice to highlight the struggles and needs of inner-city residents. He was a firm believer in some much-debated approaches to help the poor and addicted, such as needle exchange programmes as a way to reduce the spread of Aids.

He was born on January 18, 1951. In grade school, a counsellor told him he was too slow to learn and spoke poorly, and he would never fulfil his dream of becoming a lawyer.

“I was devastated,” Cummings told The Associated Press in 1996, shortly before he won his seat in Congress. “My whole life changed. I became very determined.”

It steeled Cummings to prove that counsellor wrong. He became not only a lawyer, but one of the most powerful orators in the Maryland House of Delegates, where he entered office in 1983.

He rose to become House speaker pro tem, the first black delegate to hold the position. He would begin his comments slowly, developing his theme and raising the emotional heat until it became like a sermon from the pulpit.

He was quick to note the differences between Congress and the Maryland General Assembly, which has long been controlled by Democrats.

“After coming from the state where, basically, you had a lot of people working together, it’s clear that the lines are drawn here,” Cummings said about a month after entering office in Washington in 1996.