A poor showing for former Florida Governor Jeb Bush, who was running in a distant fourth place, could mark the end of the Bush campaign and an end to his dreams of becoming a third Bush president after his father and brother.
After South Carolina, the Republican presidential campaign is about to rapidly pick up steam in March when dozens of states hold nominating contests.
Another candidate, Ohio Governor John Kasich, is concentrating on midwestern and northern states in the state-by-state contest to pick nominees for the November election. Clinton's victory in the Nevada Democratic caucuses could help calm Democratic Party worries about the strength of her campaign.
Her win denied Sanders the breakthrough win he sought in a state with a heavy minority population, but his ability to close a one-time double-digit polling lead for Clinton suggested the Democratic nominating race would be long and hard fought.
With 84 per cent of precincts reporting, Clinton was leading with 52.4 per cent of the vote to Sanders' 47.5 per cent. Vote counting was delayed in Nevada by heavy turnout.
Clinton's victory buoyed worried supporters and gave her fresh momentum as she heads into the next contest in South Carolina on February 28, where polls show her with a double-digit lead largely as a result of heavy support from black voters. "Some may have doubted us, but we never doubted each other," she told cheering supporters at a victory rally in Las Vegas. "This is your campaign."
-AAP