Washington | Former first lady Michelle Obama stole the opening night of America's first virtual convention with an excoriating attack on Donald Trump and a simple warning.

"If you think things cannot possibly get worse, trust me, they can; and they will if we don't make a change in this election," Ms Obama said at the end of a two-hour program that highlighted the economic, social and public health ravages of the pandemic, the racial tensions that unleashed the Black Lives Movement, and the growing sense of unity across a Democratic party drifting leftwards.