US presidential debate organizers vowed on Wednesday to change the rules to rein in unruly behavior after President Donald Trump repeatedly interrupted rival Joe Biden and the moderator in the candidates' taunt-filled initial prime-time encounter.

Biden suggested a mute button might help and Trump complained the Commission on Presidential Debates was siding with the Democrats in the aftermath of Tuesday's debate in Cleveland.

The 90-minute face-off triggered widespread criticism of Trump and, to a lesser extent, Biden. The Republican president repeatedly bullied Biden and questioned his intelligence, while the Democratic nominee called Trump a racist, a liar and the worst president ever.