The campaigns of Vice President Kamala Harris and former President Donald Trump are arguing in advance of their high-stakes Sept. 10 debate over whether microphones should be muted except for the candidate whose turn it is to speak.While it’s common for campaigns to quibble beforehand over debate mechanics, both Harris and Trump are under pressure to deliver a strong performance next month in Philadelphia. The first debate during this campaign led to President Joe Biden’s departure from the race.Trump on Sunday night raised the possibility that he might not show up on ABC, posting on his Truth Social network that he had watched the network’s Sunday show with a “so-called Panel of Trump Haters” and posted, “why would I do the Debate against Kamala Harris on that network?” and urging followers to “Stay tuned!!”The current dispute centers on the muting of microphones when a candidate isn’t speaking, a condition both …