US senator John McCain dead at 81

US senator John McCain, a celebrated war hero known for reaching across the aisle in an increasingly divided America, died on Saturday following a battle with brain cancer. He was 81.

"Senator John Sidney McCain III died at 4:28 pm on August 25, 2018. With the senator when he passed were his wife Cindy and their family," his office said in a statement.

"At his death, he had served the United States of America faithfully for 60 years. Sen McCain, thank you for your service," read a sign near the driveway of his home in a rural part of Sedona, Arizona, television footage showed, as a police escort accompanied the hearse that was to carry his body and local residents came bearing flowers for the late political titan.

While he had many disagreements with fellow politicians, the Republican stalwart's integrity was not at question, and condolences came swift from the highest reaches of American politics after his passing.

Ex-president Barack Obama, the Democrat to whom McCain lost the presidency in the 2008 elections, said "we are all in his debt."

"John McCain and I were members of different generations, came from completely different backgrounds and competed at the highest level of politics," Obama said in a statement.

"But we shared, for all our differences, a fidelity to something higher -- the ideals for which generations of Americans and immigrants alike have fought, marched and sacrificed."

Former vice president Al Gore -- who served under Democrat Bill Clinton -- said, "I always admired and respected John from the opposite side of the aisle, because he thrived under pressure, and would work to find common ground, no matter how hard."

President Donald Trump, who once mocked McCain's war record, said he sent his "deepest sympathies and respect."

McCain had been a rare and outspoken Republican critic of Trump, accusing him of "naivete," "egotism" and of sympathizing with autocrats.

On Capitol Hill, McCain became close friends with Senator Lindsey Graham and former senator Joe Lieberman -- a trio dubbed the "Three Amigos."

Now that the trio is missing its driving force, Graham wrote that "America and Freedom have lost one of her greatest champions... And I've lost one of my dearest friends and mentor."

McCain, who was tortured during his five years as a prisoner of war in Vietnam, stopped treatment from an aggressive form of cancer earlier this week, his family saying "the progress of disease and the inexorable advance of age render their verdict."

He had spent more than three decades in the Senate, looming large in debates over war and peace and the moral direction of the nation. Before joining the upper chamber, he served as a US representative from 1983 to 1987.

McCain had not been on the Senate floor in months, remaining at his Arizona home for treatment of glioblastoma -- the same form of brain cancer that took the life of another Senate giant, Democrat Ted Kennedy, in 2009.