Elijah E. Cummings, a 13-term representative from Maryland who chaired the House Oversight and Reform Committee, has died of health complications aged 68

President Trump ordered American flags around the world to be flown at half-staff in honor of Elijah E. Cummings after the senior Democrat died aged 68.

Cummings, who served as chair of the House Oversight and Reform Committee, passed away of 'complications concerning longstanding health challenges' in hospice care at Johns Hopkins Hospital in his hometown of Baltimore at 2.45am on Thursday, his office said.

Dozens of tributes have poured in from politicians on both sides of the aisle, honoring the 13-term representative from Maryland who was known on Capitol Hill for his commanding presence, fierce resolve and unwavering commitment to preserving democracy.

Trump, who frequently sparred with Cummings over major policy issues, ordered that American flags worldwide be flown at half-mast.

'My warmest condolences to the family and many friends of Congressman Elijah Cummings,' Trump tweeted Thursday morning.

'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' wife of 11 years Maya Rockeymoore gave a touching tribute to her late husband.

'Congressman Cummings was an honorable man who proudly served his district and the nation with dignity, integrity, compassion and humility,' the 48-year-old chairwoman of the Maryland Democratic Party said.

'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.'

Former President Barack Obama also issued a statement, saying he and his wife Michelle are 'heartbroken' over Cummings' passing.

'As Chairman of the House Oversight Committee, he showed us all not only the importance of checks and balances within our democracy, but also the necessity of good people stewarding it,' Obama wrote.

'Steely yet compassionate, principled yet open to new perspectives, Chairman Cummings remained steadfast in his pursuit of truth, justice, and reconciliation. It's a tribute to his native Baltimore that one of its own brought such character, tact, and resolve into the halls of power every day.'

Cummings' wife of 11 years Maya Rockeymoore, 48, led the tributes to her late husband. 'Congressman Cummings was an honorable man who proudly served his district and the nation with dignity, integrity, compassion and humility,' Rockeymoore said. The couple, who married in 2008, are pictured together at a state dinner in 2014

The Committee on Oversight and Reform room was adorned in black in honor of its late chairman. A black stole and bouquet of flowers are seen at Cummings' seat

President Donald Trump, who frequently sparred with Cummings, ordered that American flags worldwide be flown at half-mast. A lowered flag is seen at the White House

Despite their frequent sparring, President Trump tweeted a tribute to Cummings' on Thursday, saying 'his work and voice on so many fronts will be very hard, if not impossible, to replace!'

Cummings' death comes two years after he had surgery to repair his aortic valve, and a month after he was admitted to a hospital for further treatment.

At the time of his hospitalization in early September, Cummings predicted that he would be back in Washington within a week.

His declining health meant that he had been using a wheelchair to get around Washington and used a walker in order to stand.

Nevertheless, he remained an imposing figure in Congress - as evidenced by the overwhelming response to his death by fellow lawmakers and the public.

Among those paying tribute were Democratic presidential hopefuls Kamala Harris, Elizabeth Warren, Joe Biden, Beto O'Rourke, Cory Booker, Julian Castro and Amy Klobuchar.

California Senator Harris wrote on Twitter: 'We lost a giant today. Congressman Elijah Cummings was a fearless leader, a protector of democracy, and a fighter for the people of Maryland. Our world is dimmer without him in it.'

Former President Barack Obama issued the statement above on Thursday morning

Cummings was an early supporter of Barack Obama's presidential bid in 2008. The pair are pictured together at a campaign rally in 2007

'Rep Elijah Cummings was a giant in the House, an unwavering champion for his district and all Americans, and a dear friend. My heart goes out to his wife Maya and his family,' Massachusetts Sen Warren tweeted.

'Good people everywhere will miss his rumbling voice, his kind heart, and his deep conviction that every human being has worth. Rest in power, Elijah.'

Former Vice President Biden released a long statement, calling Cummings a 'lion of democracy and a powerful ally in the fight for the soul of our nation'.

'Today our country lost a true leader. Congressman Elijah Cummings was a friend, a passionate fighter for justice, and a powerful voice of moral conscience in our government who served his country for decades with dignity and integrity. I'm blessed to have known him,' Booker tweeted.

O'Rourke wrote on Twitter: 'We lost one of our best. A son of sharecroppers, who went on to represent one of our greatest cities; a fighter for justice, who always led with love—Rep. Elijah Cummings was everything right about America. He is already missed, but his legacy will be with us forever.'

'We are struck this morning to hear the news about the passing of Congressman Elijah Cummings. His death is a tragedy not just for the city of Baltimore, but for our entire nation, and for all of those who fight for justice,' Castro tweeted.

'We've lost a leader like no other. Elijah Cummings was a lion when standing up for his beloved Baltimore & rights & truth. But he was also so kind, including to brand new senators like me a decade ago. His advice was as true as his love for his country,' Klobuchar said.

Cummings worked closely with many of the candidates now hoping to beat Trump in the 2020 presidency, including Joe Biden (left in 2003) and Elizabeth Warren (left in 2013)

Joe Biden released a long statement, calling Cummings a 'lion of democracy and a powerful ally in the fight for the soul of our nation'

Rep Debbie Wasserman Schultz, who served on the Oversight Committee with Cummings, called him 'a king, principled leader' and 'one of my dearest friends and mentors'.

'My heart is broken, as I weep personally and for his family and community,' the senator wrote on Twitter. 'Elijah Cummings' unmatched integrity and leadership leaves a remarkable legacy.'

Rep Hakeem Jeffries, House Democratic caucus chairman and a fellow member of the Congressional Black Caucus, tweeted: 'Deeply saddened by the passing of Chairman Elijah Cummings.

'He spoke truth to power, defended the disenfranchised and represented West Baltimore with strength and dignity.

'Congress has lost a Champion. Heaven has gained an Angel of Justice. May he forever #RestInPower.'

Rep Steve Cohen (D-Tennessee) wrote on Twitter: 'A Giant of integrity and knowledge has fallen. He defended the Constitution and acted with grace.'

House Speaker Nancy Pelosi said she was 'personally devastated by Cummings' passing, calling him 'our North Star'.

'In the House, Elijah was our North Star. 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,' Pelosi said.

'His principled leadership as Chair of the Committee on Oversight and Reform was the perfect testament to his commitment to restoring honesty and honor to government, and leaves a powerful legacy for years to come.'

Cummings has been described by colleagues and loved ones as a formidable orator who passionately advocated for the poor in his district, which included a large portion of Baltimore

Cummings is seen in 2004 with then-presidential candidate John Kerry (center) and Leadership Conference on Civli Rights Executive Director Wade Henderson (right) at an event commemorating the 50th anniversary of Brown v Board of Education in Topeka, Kansas

The Maryland congressman is seen at a protest over the police-involved death of Freddie Gray in Baltimore in April 2015

Cummings posted the photo above with his two daughters, Jennifer and Adria, to commemorate Father's Day in June of this year

Cummings is survived by his wife Rockeymoore, whom he married in 2008, as well as his two daughters, Jennifer and Adria, and a son from previous relationships.

He was born in Baltimore on January 18, 1951, to Robert Cummings Sr and Ruth Elma Cummings, who moved to Maryland after sharecropping on South Carolina land where their ancestors were enslaved. He was one of seven children.

In grade school, a counselor told Cummings he was too slow to learn and spoke poorly, and he would never fulfill 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 counselor wrong.

He became not only a lawyer, but one of the most powerful orators in the statehouse, where he entered office in 1983.

Cummings was born in Baltimore on January 18, 1951, to Robert Cummings Sr and Ruth Elma Cummings, who were sharecroppers on land where their ancestors were enslaved. He is pictured in his early 20s in 1973 (left) and two years before he joined Congress in 1994 (right)

Cummings ran for Maryland state delegate in 1982 and won. He is pictured with folk singer Vera Hall right) in 1984

Cummings is pictured with then-President Bill Clinton in 1998

Cummings cruised to big victories in the overwhelmingly Democratic district, which had given Maryland its first black congressman in 1970 when Parren Mitchell was elected.

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

In 1996, Cummings joined US Congress after winning a special election to replace former Rep Kweisi Mfume, who left to lead the NAACP.

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.

Cummings chaired the Congressional Black Caucus from 2003 to 2004, employing a hard-charging, explore-every-option style to put the group in the national spotlight.

In January 2019, Cummings took over as chair of the House Oversight and Reform Committee

He was an early supporter of Barack Obama's presidential bid in 2008. And by 2016, Cummings 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.

In January 2019, he became chair of the House Oversight and Reform Committee.

As chairman, Cummings led multiple investigations into Trump's governmental dealings - including attempts to get hold of the president's tax returns.

The investigations angered the president, who went on to personally attack Cummings in July when he criticized conditions in detention centers at the US southern border.

Cummings famously rowed with Trump over the summer after the president called Baltimore - a large portion of which falls in the congressman's district - 'rat-infested'

The outraged president defended the border detention centers as 'clean, efficient and well run, just very crowded', and then claimed the facilities are superior to Cummings' own district in Maryland.

'Cumming District is a disgusting, rat and rodent infested mess. If he spent more time in Baltimore, maybe he could help clean up this very dangerous & filthy place,' Trump tweeted.

'Why is so much money sent to the Elijah Cummings district when it is considered the worst run and most dangerous anywhere in the United States,' Trump wondered in another tweet.

'No human being would want to live there. Where is all this money going? How much is stolen? Investigate this corrupt mess immediately!'

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 behavior,' Cummings said in a speech at the National Press Club.

Despite his feud with Trump, the pair only had one face-to-face meeting, according to the Baltimore Sun.

That meeting came in 2017 when Cummings was working with Trump on a plan to lower drug prices.

Cummings told the President: 'Very soon you and I will be dancing with the angels. The thing that you and I need to do is figure out what we can do — what present can we bring to generations unborn?'

The Oversight Committee - as the main investigative committee of the House - was one of six involved in the impeachment inquiry into Trump and was spearheading efforts to gather evidence, alongside the Intelligence Committee.

Rep Mark Meadows - a North Carolina Republican who shared a close relationship with Cummings despite their starkly different political beliefs - reacted to his death by saying: 'I am heartbroken. Truly heartbroken.'

Freshman Rep Alexandria Ocasio-Cortez - who is also known for her imposing presence on the congressional floor- tweeted: 'A devastating loss for our country. Chairman Cummings was a giant: a universally respected leader who brought profound insight, commitment, and moral fortitude to Congress.

'His guidance and vision was an enormous gift. I will forever cherish his example. May he rest in power.'

Rep Carolyn Maloney, who will become the Acting Chair of the House Oversight committee following Cummings' death, said in a statement: 'I'm deeply saddened by the news of Chairman Cummings' passing. Our nation has not only lost a true leader and pioneer, but I have lost a dear friend and mentor.

'In an era where our politics have been plagued by coarseness and personal attacks, Elijah represented grace, dignity and empathy under the most trying of circumstances.

'His legacy - his fight for fairness, justice, and equality - should be an inspiration to us all. My heart goes out to his family.'

Former Secretary of State and 2016 presidential candidate Hillary Clinton wrote on Twitter: 'America lost a giant with the passing of Rep. Elijah Cummings, a man of principle who championed truth, justice and kindness. He fiercely loved his country and the people he served. Rest In Peace, my friend.'

White House adviser Kellyanne Conway tweeted: 'Sad to learn of the passing of longtime, passionate public servant Rep. Elijah Cummings. May he Rest In Peace. Lifting up his family, friends and colleagues in prayer.'

Many of the tributes came from outside Washington, including one from Martin Luther King Jr's daughter Bernice King.

'What a life of passionate service and courage. My heartfelt condolences to your wife, your family, the City of Baltimore, the United States and the world. Your life blessed a multitude,' she wrote.

The Baltimore archdiocese tweeted that Cummings 'generously shared his God-given gifts and talents w/the people of his beloved city, state and nation for so many years. We give thanks for his dedicated service and pray for the repose of his soul.'