It should have been a triumphant night for Hillary Clinton when her rival Bernie Sanders gave a rousing speech urging his supporters to vote for her in the Nov. 8 U.S. presidential election.

Instead it turned into a sign of potential trouble for her White House bid. His speech Monday to the Democratic National Convention in Philadelphia urging the party to unite against Republican Donald Trump was met with some jeers when he endorsed Clinton — a sign he had lost control of his own movement.

"I'm beyond disappointed," California delegate Aleece Depuey, 49, said after Sanders sought to rally support for his onetime rival.