Alexander Haig failed in his 1988 presidential bid
Former US Secretary of State Alexander Haig has died at the age of 85.
Mr Haig had been admitted to Johns Hopkins Hospital in Baltimore on 28 January with complications associated with an infection, his family said.
He was chief-of-staff to President Richard Nixon during the Watergate scandal in the early 1970s.
Mr Haig was perhaps best known for his bungled response when President Ronald Reagan was shot in 1981, erroneously telling reporters he was "in control".
Mr Haig maintained that he was simply trying to keep the country calm, but he was widely derided for apparently trying to overstep his authority.
Cold War warrior
A spokesman for Johns Hopkins Hospital, Gary Stephenson, said that Mr Haig had passed away at about 0130 (0530 GMT) on Saturday.
BBC defence correspondent Rob Watson says Mr Haig was the ultimate Cold War warrior.
A decorated hero in both the Korean and Vietnam wars, he rose to the rank of general before continuing the fight via the conservative politics of the Republican Party of the 1970s and 80s, our correspondent says.
In 1973, he was asked to take over as President Nixon's chief of staff at a time when the administration was in serious trouble.
Mr Haig was widely credited with saving the presidency from complete collapse over Watergate, and persuading Nixon to resign.
He then stayed on as chief of staff to Gerald Ford, Nixon's successor.
After a brief return to the military as Nato's Supreme Allied Commander, Mr Haig was back in Washington in 1981 as President Reagan's hawkish secretary of state.
During that time, he courted controversy by suggesting the possible use of nuclear weapons as a warning to the Soviets.
"There are contingency plans in the Nato doctrine to fire a nuclear weapon for demonstrative purposes, to demonstrate to the other side that they are exceeding the limits of toleration in the conventional area," he said.
He also led failed US diplomatic efforts to negotiate between the UK and Argentina before the Falklands War, in the so-called "peace-shuttle" talks.
In 1988, he ran for the Republican presidential nomination but was beaten by the more moderate Vice-President George H W Bush, a loss which marked the end of his political career.