Jesse Helms had revelled in his conservative image
Former US Republican Senator Jesse Helms - a leading conservative politician - has died aged 86, officials say.
He died early on Friday of natural causes in Raleigh, North Carolina, his former chief of staff said.
Mr Helms had served five terms in the Senate representing North Carolina before stepping down in 2003.
He was dubbed "Senator No" for blocking many policies he saw as contrary to his conservative view of the world.
Mr Helms was chairman of the influential Senate Foreign Relations Committee, becoming the first lawmaker to address the UN Security Council.
Mr Helms died at 0115 local time in Raleigh, the Jesse Helms Center said.
"He was very comfortable," Jimmy Broughton, Mr Helm's former chief of staff, was quoted as saying by the Associated Press news agency.
Jesse Helms started political life as a Democrat, albeit a conservative-sounding one, who worked as a newspaper editor and a television commentator.
He first went to the Senate to represent North Carolina in 1972.
He had polarised voters in the southern state and opinion throughout the country, correspondents say.
He became known for his refusal to ratify international treaties and obstinate blocking of other executive actions, the BBC's Jonny Dymond says.
It was Mr Helms who stopped the US paying its dues to the UN; Mr Helms who blocked ratification of the Comprehensive Test Ban Treaty, and the Kyoto Protocol on global warming; and Mr Helms who opposed the use of US troops in Bosnia.
"I will not support sending American soldiers to fight and to die for the sake of an agreement not yet reached which may offer no more than the promise of a brief pause while all sides prepare for the next round of Balkan wars," Mr Helms said.
Before he became chairman of the Senate Foreign Relations Committee, he attacked accords such as the Panama Canal Treaty and the Salt II arms reduction pact.
As committee chairman he clashed with the Clinton administration. Its multilateral approach to foreign relations did not fit in with his view of how America should operate.
He also helped sink the administration's attempts to ratify the Comprehensive Test Ban Treaty in 1999, and in 2000 made it clear that a modified 1972 Anti-Ballistic Missile Treaty would not pass the Senate.
Mr Helms never cared very much what his critics thought, our correspondent says - and if he had, he certainly would not have been so outspoken about what he perceived to be the ills of modern life.
But there was also a compassionate side to Mr Helms, who had campaigned for the passage of a debt relief bill through Congress, our correspondent says.