These numbers are even worse for Obama than in the West Virginia primary one week ago, where just 36 percent of Clinton supporters said they would back Obama.
Analysts say the right thing for Obama to do is to give Clinton a graceful exit.
He extended an olive branch in his speech Tuesday, congratulating Clinton for her victory in Kentucky.
The Obama camp also avoided demanding that she get out of the race.
Simon Rosenberg, president of Democratic think tank NDN, said: "Everybody in the Democratic family knows today that it's going to be hard to put this party back together."
But whatever the challenges ahead, the Democrats have a political landscape tilted in their favor.
U.S. voters are opposed to the Iraq war, alarmed about the weak economy and convinced the country is headed in the wrong direction.
"If the Democrats can't win with this deck of cards, I'm not sure we should win," says Mark Siegel, a former official of the Democratic National Committee.
(Xinhua News Agency May 22, 2008)
