With just 15 days left until the scheduled Sept. 10 presidential debate between Vice President Kamala Harris and former President Donald Trump, negotiations between their two campaigns have hit an impasse over whether the candidates’ microphones will be muted when it is not their turn to speak, according to four people familiar with the issue. 

In June, President Joe Biden’s campaign came to an agreement with Trump’s: There would be two debates — CNN’s on June 27 and ABC’s on Sept. 10 — conducted by mutually negotiated rules. One of the Biden team’s demands — which the Trump team agreed to — was that microphones “will be muted throughout the debate except for the candidate whose turn it is to speak,” as CNN announced on June 15.

But Biden is no longer running for president. And Harris’ campaign wants the microphones to be hot at all times during the ABC debate — as has historically been the case at presidential debates.