Former President Donald Trump’s campaign is casting fresh doubt on whether a September 10 debate will take place on ABC amid a dispute over the rules, a source familiar with the matter tells CNN. Trump’s team, according to the source, would like for the microphones to be muted throughout the debate except for the candidate whose turn it is to speak, as was the case during the first debate with President Joe Biden. The Harris campaign, however, is requesting that ABC and other networks...