A controversial appointment: Outspoken former Republican senator Chuck Hagel to be sworn in as US Defence Secretary

Chuck Hagel is set to be sworn in as Barack Obama’s latest Defence Secretary today, ending one of the most controversial appointment sagas in US history.

The outspoken former Republican senator, 66, won two Purple Hearts as an infantry squad leader in Vietnam, yet has become one of the most divisive figures in Washington as a result of his record since embarking on a political career as a Senator for Nebraska in 1997.

Despite being nominated for his new post by Barack Obama in January, his confirmation has dragged on for more than seven weeks after Senate Republicans denied Mr Obama the 60 votes he needed to end debate on Mr Hagel’s appointment during a session on Valentine’s Day. It was the first time in history that a nominee for the post of Defence Secretary had been filibustered.

For civil rights groups Mr Hagel is controversial for calling former US ambassador to Luxembourg, James Hormel, an "openly aggressive gay" in 1998, even though he subsequently apologised for the remark. The right doesn’t like him because he criticised the power of what he called "the Jewish lobby" in Washington, when knee-jerk support for Israel is virtually obligatory on Capitol Hill.

And many of his erstwhile Senate colleagues still resent how, after initially voting to authorise the 2003 invasion of Iraq, he turned his party against him by becoming a fierce critic of a war launched by a Republican president, and then advocated that instead of piling more sanctions on Iran, the US should instead sit down and talk with the regime. It was his past war record that informed his second life in politics. "I owe it to those guys to never let this happen again to the country," he said when questioned over his opposition to Iraq.

Born in North Platte, Nebraska, in 1946, Chuck Hagel lost his father, a veteran of the Second World War, when he was 16 years old. He studied at the University of Nebraska before joining the Army in 1967 and being posted to Vietnam, where he served with his brother in the 9 Infantry Division.

The Hagels are believed to be the only siblings to have fought alongside one another in the conflict. After returning home he briefly presented a radio talk show in Omaha before being hired by Republican congressman John McCollister. His career then took him into lobbying, and 1980 he was an organiser for Ronald Reagan’s successful presidential campaign. He made his fortune in telecoms through his company Vanguard Cellular and also worked in banking before being elected to the Senate in 1997. He retired in 2008 and secured a professorship at Georgetown University in Washington, while also serving on the boards of a number of companies, including Chevron.

He has long been admired by the President – and even accompanied then candidate-Obama on a visit to Israel, Iraq and Afghanistan in the summer of 2008. He is also strongly backed by stalwarts of the foreign policy establishment, including former national security advisers Zbigniew Brzezinski and Brent Scowcroft. But his return to politics has not been straightforward.

One of Mr Hagel’s fiercest critics in Washington was once one of his closest friends, the former Republican presidential nominee John McCain. Both are Vietnam veterans and often travelled together to Iraq and Afghanistan during Mr Hagel’s 12 years in the Senate. That friendship was seen to have fallen apart, however, precisely because they took directly opposing positions on the 2007 surge, a strategy Mr Hagel said at the time would be “the most dangerous foreign-policy blunder in this country since Vietnam”.

The pair clashed when Mr Hagel was called to the Senate in January to face questions from the House Foreign Relations Committee, during which Mr McCain accused him of being “on the wrong side of history”. Afterwards Mr McCain said Mr Hagel’s appearance was one of the most “unimpressive” he had ever seen. Despite this he is expected to finally secure his nomination today, after a number of Republicans reversed their opposition and agreed to vote for him.