FACTBOX: Presidential candidate John McCain

(Reuters) - Sen. John McCain has secured the Republican nomination for U.S. president. Here are some facts about McCain:

* If elected, McCain, who turns 72 in August, would be the oldest person to assume the U.S. presidency.

* From a celebrated Navy family, McCain is the son and grandson of four-star admirals and he followed in their footsteps by attending the U.S. Naval Academy.

* On his 23rd combat mission over Vietnam in 1967, he was shot down. He spent 5 1/2 years in captivity, including two in solitary confinement, and was subjected to frequent beatings and torture. In the Senate, he has been a critic of harsh interrogation techniques such as "waterboarding" or simulated drowning.

* McCain was seen as a maverick in his campaign for the 2000 Republican presidential nomination when he gave then-Texas Gov. George W. Bush a scare by winning the first-in-the-nation primary state of New Hampshire by 18 percentage points. But he lost to Bush in South Carolina after bitter state primary campaigns.

* McCain has vigorously supported the unpopular Iraq war as many Americans are weary of the conflict and eager to get U.S. troops home. McCain has criticized the way the war was conducted initially, saying the United States should never go to war without a comprehensive plan for success.

* First elected to the U.S. House of Representatives in 1982, McCain won the first of four terms in the Senate in 1986.

* In Congress, McCain has been a pro-business conservative, free-market advocate and abortion foe but he has voted against the Republican majority on several high-profile bills. He has made campaign finance reform a signature concern, which led to the passage of the McCain-Feingold Act in 2002.

* He was among five senators investigated for taking contributions from savings and loan financier Charles Keating. In 1991, the Senate ethics committee said McCain exercised poor judgment in the matter but it cleared him of any wrongdoing.

(Writing by Paul Grant and Patricia Zengerle)

(To read more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at blogs.reuters.com/trail08/)