Edwards' wife, Elizabeth, who has cancer and is a well-known political figure, did not accompany Edwards to the Obama rally. She has not endorsed either candidate.
Clinton's campaign shrugged off the endorsement.
'FAR FROM OVER'
"We respect John Edwards, but as the voters of West Virginia showed last night, this thing is far from over," her campaign chairman, Terry McAuliffe, said in a statement.
The New York senator spent Wednesday in Washington doing media interviews and meeting with donors. She promised to keep running until the last of the five remaining state contests concludes on June 3.
"We don't have a nominee yet and until we do, I'm going to be making my case," she said on Fox News.
Clinton's campaign is $20 million (10.3 million pounds) in debt but McAuliffe said she had the resources to compete with Obama and described her donors as "very excited, ready to go and ready to help."
Clinton added one superdelegate endorsement on Wednesday.
A delegate count by MSNBC gives Obama 1,885 delegates to Clinton's 1,722 - both short of the 2,025 needed to clinch the nomination. To win, both need superdelegates, with whom Obama has been gaining ground for weeks.
He also picked up the backing of three former chairmen of the Securities and Exchange Commission, including William Donaldson, who was appointed by Republican President George W. Bush.
Obama spent the day in Michigan, where he touted plans for a $150 billion clean technologies fund to create new jobs and promote fuel-efficient vehicles. Focusing on November's contest with McCain, Obama said the Arizona senator "is not offering new solutions or economic policies that are different from what George Bush has given us for eight long years."
Obama's visit to Michigan was his first since he signed a pledge last year promising not to campaign in the state because of its dispute with the national party over the timing of its primary election.
Clinton won in Michigan and Obama's name was not on the ballot. She also won a disputed race in Florida and is pushing for delegates from both states to be seated at the convention.
Five more contests remain in the Democratic nominating battle, with a combined 189 delegates at stake. Oregon and Kentucky vote on May 20, Puerto Rico on June 1, and Montana and South Dakota on June 3.
