Democratic presidential candidate John Kerry and his running mate, John Edwards, have launched their joint campaign for the White House.
The two men come from different backgrounds
The two men kicked off a multi-state tour in Cleveland, Ohio.
"We're ready to take back the White House," Mr Kerry told supporters. Mr Edwards said: "We are going to restore real American values to this country."
The Republicans hit back, with President George W Bush casting doubt on Mr Edwards' political experience.
Mr Edwards, 51, is a self-made millionaire who has served only one term in the US Senate, representing North Carolina.
Ohio is set to be one of the most contested states in the election.
The state has voted for the winner of every presidential election since 1964 and no Republican has ever won the White House without victory there.
Mr Kerry began heaping praise on his choice before setting out the reasons why Americans should vote the Democrats back into the White House.
"We think this is a dream team," he said.
"We've got better vision. We've got better ideas. We've got real plans. We've got a better sense of what's happening to America."
Mr Edwards reciprocated - saying Mr Kerry would always tell America the truth.
In a reference to the Iraq war controversy, Mr Edwards said: "When John Kerry is president of the United States, no young American will ever go to war needlessly because America has decided to go it alone."
"The truth is, we, America - we need a president that will lead the world, not bully it."
Democrats hope Mr Edwards' populist touch will attract swing voters and bring support from key Southern states.
Critics have suggested that the former trial lawyer and Democratic grassroots favourite lacks experience in politics, but observers say his Southern, more socially conservative politics may help to offset Mr Kerry's north-eastern liberal image in the run-up to November's election.
But the Republicans have already seized on his lack of experience.
President Bush, on a visit to Mr Edwards' home state of North Carolina, was asked by a reporter about the differences between Mr Edwards - "described as charming, engaging, a nimble campaigner, a populist, and even sexy" - and his Vice-President Dick Cheney.
He replied: "Dick Cheney can be president."
The Kerry-Edwards ticket will be formally nominated at the Democratic National Convention in Boston at the end of July, to run against the Bush-Cheney team.
A CNN/USA Today/Gallup poll taken after Mr Kerry announced his running mate on Tuesday, found that 64% of the 553 registered voters interviewed saw the choice of Mr Edwards as excellent or pretty good, with 28% saying it was fair or poor.
Mr Edwards had a favourable approval rating of 54% - leading President Bush by one percentage point.
However, 66% said Mr Edwards' appointment had no effect on who they would vote for in November.
Similar findings came in another poll by NBC News - of 504 people - which also found 49% support for the Kerry-Edwards team and 41% for the incumbents.
Both polls had a margin of error of five percentage points.