Edwards nod gives Obama presidential race boost

Mr Edwards's endorsement dealt a sharp blow to Mr Obama's rival Hillary Clinton.

A day earlier, she had sought to convince Democrats that her victory in West Virginia on the strength of white working-class voters was evidence that her campaign still had signs of life.

But Mr Edwards, who had based much of his candidacy on supporting working-class voters, made a surprise appearance with the Democratic front-runner in Grand Rapids, Michigan, a critical general election battleground state.

Mr Edwards said that Mr Obama "stands with me" in a fight to cut poverty in half within 10 years.

In the US, Mr Obama vowed: "You should never be homeless, you should never be hungry" and he pledged to "lift up every American out of poverty."

Earlier, he promised to pump billions of dollars into efforts to keep manufacturing jobs, telling workers at a Chrysler factory in Michigan that he would pump an extra $200 million (£103 million) a year into efforts to revitalise the manufacturing sector.