Mitt Romney has won Michigan's Republican presidential primary, relaunching his campaign after second-place finishes in Iowa and New Hampshire.

Despite leading in a number of pre-election opinion polls, John McCain came in second. He was already in South Carolina on Tuesday, campaigning for its primary.

Mike Huckabee, the winner in Iowa on 3 January, took third place in Michigan, as he did in New Hampshire last week.

Turnout was reported to have been low in the primary, possibly as a result of low temperatures throughout the state

Hillary Clinton won Michigan's Democratic Party primary, although the result is receiving little attention, because of a ruling by party bosses rendering the contest invalid.