WASHINGTON (REUTERS) - John Lewis, a pioneer of the civil rights movement and long-time member of the US House of Representatives, died on Friday (July 18), a passing that prompted tributes from leaders across the political spectrum.

A Democratic member of Congress from Atlanta, Lewis had announced in December that he had advanced pancreatic cancer. He was 80.

Lewis was a protege of the Reverend Martin Luther King Jr, whom he met after writing to him when Lewis was just 18. He was the last surviving speaker from the 1963 March on Washington, having stood beside King when he made his "I Have a Dream" speech.

"Saddened to hear the news of civil rights hero John Lewis passing. Melania and I send our prayers to he and his family," US President Donald Trump wrote on Twitter on Saturday.

Earlier, Trump ordered flags to fly at half-staff throughout the day.

Lewis tangled with Trump even before the Republican took office. In January 2017, Lewis said he did not view Trump as a "legitimate" president because of Russian meddling in the 2016 election to boost his candidacy.

Trump drew criticism even from fellow Republicans when he called Lewis "all talk" and "no action."

Lewis kept up the fight for civil rights and human rights until the end of his life, inspiring others with calls to make "Good Trouble."

"He loved this country so much that he risked his life and his blood so that it might live up to its promise," former president Barack Obama said in a statement.

"And through the decades, he not only gave all of himself to the cause of freedom and justice, but inspired generations that followed to try to live up to his example."

Former US president Bill Clinton and former Secretary of State Hillary Clinton in a joint statement, "We have lost a giant. John Lewis gave all he had to redeem America's unmet promise of equality and justice for all, and to create a place for us to build a more perfect union together."

House Speaker Nancy Pelosi called Lewis "a titan of the civil rights movement whose goodness, faith and bravery transformed our nation."

RECENT PROTESTS

In 2016, Lewis led a "sit-in" by House Democrats to demand a vote on gun regulations.

He made his last public appearance last month, as protests for racial justice swept the United States and the world.

Using a cane, Lewis walked with Washington Mayor Muriel Bowser on a street by the White House that Bowser had just renamed Black Lives Matter Plaza. It had just been dedicated with a large yellow mural - large enough to be seen from space - reading "Black Lives Matter."

Tributes quickly began pouring in from other politicians, Lewis' fellow Democrats and Republicans.

The Republican Majority Leader of the US Senate, Mitch McConnell, said Lewis had a place "among the giants of American history" even before he was elected to Congress, noting his rise from a family of sharecroppers in segregated Alabama.

"The Senate and the nation mourn the loss of Congressman John Lewis, a pioneering civil rights leader who put his life on the line to fight racism, promote equal rights, and bring our nation into greater alignment with its founding principles," McConnell said.

"John Lewis was an icon who fought with every ounce of his being to advance the cause of civil rights for all Americans," said Senator Kamala Harris, the first African American to represent California in the Senate, on Twitter.

"I'm devastated for his family, friends, staff - and all those whose lives he touched."