First Lady Michelle Obama has backed her husband's one-time rival for the Presidency telling Democrats, "In this election, I'm with her."

Taking aim at Republican presidential candidate Donald Trump, she said Hilary Clinton, "is someone who understands that the issues a president faces are not black and white, and can not be boiled down to 140 characters."

Her address comes amid an a raucous opening to the Democratic convention, as supporters of Hillary Clinton and Bernie Sanders drowned out the opening proceedings with competing cheers and chants on Monday and as discord enveloped the first day of the Democratic convention to nominate Clinton for president.

Sanders complained bitterly during the primary process that the party leadership was working against him. Some of his backers are reluctant to get behind Clinton, seeing her as a member of the Washington political elite who pays lip service to their goals of reining in Wall Street and eradicating income inequality.

The scenes of booing at the convention in Philadelphia were a setback to Democratic officials' attempts to present the gathering as a smoothly run show of party unity in contrast to the volatile campaign of Republican nominee Donald Trump.

While Sanders has endorsed Clinton, the former first lady faces the task of attracting his backers as she battles Trump. The New York businessman pulled ahead in at least one opinion poll, after lagging Clinton in most national surveys for months.