The status of an anticipated debate between US presidential candidates Donald Trump and Vice President Kamala Harris is up in the air as the two campaigns squabble over details.

On Monday, the Harris campaign said the dispute centres over whether microphones will be muted while the other candidate is speaking, a feature meant to decrease interruptions and employed during an earlier debate between former President Trump and then-candidate and current President Joe Biden.

The Harris campaign now wants to see that feature reversed. Trump has also accused ABC News, the network hosting the September 10 debate, of bias against him.

“I ask, why would I do the Debate against Kamala Harris on that network?” Trump said in a social media post on Sunday.

The microphone-muting feature was a condition previously established by the Biden campaign, which believed it would limit Trump from his typical outbursts on stage and allow for a smoother event.

Biden suspended his bid for a second term last month after a disastrous debate performance against Trump in June that underscored concerns over his age and cognitive state. The Democratic Party rallied around Harris as its new candidate for the November 5 election soon thereafter.

The Harris campaign is now fighting to reverse the microphone rule, believing that it helped Trump by making him appear more disciplined than he really is and denying viewers the chance to make an honest assessment of his temperament.

“Trump’s handlers prefer the muted microphone because they don’t think their candidate can act presidential for 90 minutes on his own,” Harris campaign spokesperson Brian Fallon said in a statement on Monday.