Barack Obama speaks during Democratic National Committee event at the Austin Music Hall on March 11, 2016 in Austin, Texas. (Photo credit: MANDEL NGAN/AFP via Getty Images) WASHINGTON (AP) - Barack Obama will issue a blistering rebuke of President Donald Trump in Wednesday's Democratic Party convention, accusing his successor of unleashing America’s “worst impulses” and treating the presidency as a reality show “to get the attention he craves."In excerpts released ahead of his address, the former president also puts the stakes in the November election in stark terms, warning that the future of American democracy is on the line in the race between Trump and Democratic nominee Joe Biden.“I am also asking you to believe in your own ability —.