Senator John McCain, the Vietnam war hero turned senator and presidential candidate, has died aged 81. Mr McCain died on Saturday in Arizona surrounded by his family, a statement from his office said.
He was diagnosed with an aggressive brain tumour in July 2017 and had been undergoing medical treatment.
His family announced on Friday that Mr McCain, who left Washington in December, had decided to cease treatment.
The six-term senator for Arizona and 2008 Republican presidential nominee was diagnosed after doctors discovered his tumour during surgery to remove a blood clot from above his left eye last July.
His family said he would lie in state in Phoenix, Arizona, and in Washington DC before a funeral at the Washington National Cathedral and his burial in Annapolis, Maryland.
Former presidents Barack Obama and George W Bush are expected to give eulogies.
The son and grandson of Navy admirals, Mr McCain was a fighter pilot during the war in Vietnam. When his plane was shot down, he spent more than five years as a prisoner of war.
While in the custody of his captors, he suffered torture that left him with lasting disabilities.
In politics, he took a conservative line on many issues, including opposing abortion and advocating higher defence spending. He backed the 2003 invasion of Iraq and criticised President Obama for not intervening more in the Syrian civil war.
However, he also gained a reputation as a Republican maverick who was willing to cross party lines on a range of issues.
In July last year, just after his diagnosis, he took part in a late-night Senate session and gave the deciding vote - with a thumbs-down gesture - against partially repealing the contentious Obamacare healthcare law. The move reportedly infuriated Mr Trump.
Mr McCain also criticised President Trump's hard-line rhetoric on illegal immigration and his attacks on the media.