Kerry ahead in race to take on Bush
Senator John Kerry has won crushing caucus victories in Michigan and Washington state.
The Democratic is now front-runner to take on George Bush in the next US election.
He held a double-digit lead in Washington, and was gaining more than 50% of the vote in a multi-candidate race in Michigan.
Howard Dean, shut out in the primary season to date, suffered a fresh blow when the head of a major union decided to withdraw his support.
Mr Kerry said: "This week George Bush and the Republican smear machine have trotted out the same old tired lines of attack that they've used before to divide this nation and to evade the real issues before us.
"They're extreme, we're mainstream and we're going to stand up and fight back."
Aides said the speech was designed to reassure the party faithful that he would fight far harder against Republican attacks than Michael Dukakis, the former Massachusetts governor who led the party to defeat in 1988.
Like Mr Dean, Senator John Edwards and retired General Wesley Clark signalled in advance that they had scant hopes for success during the day. They aimed their efforts at states still ahead on the campaign calendar.
