US presidential debate organisers have vowed to change the rules to rein in unruly behaviour after President Donald Trump repeatedly interrupted rival Joe Biden and the moderator in the candidates' chaotic encounter.
The Commission on Presidential Debates says it will adopt changes to allow for a "more orderly discussion," with the next debate scheduled for October 15 in Miami. There was immediate speculation that this could include a mute button to limit interruptions.
The 90-minute face-off in Cleveland on Tuesday triggered widespread criticism of Trump and, to a lesser extent, Biden. The Republican president repeatedly attempted to bulldoze over Biden speaking and questioned his intelligence, while the Democratic nominee called Trump a racist, a liar and the worst president ever.
Biden's campaign raised nearly $10 million during the debate, a campaign aide said, adding to the Democrat's financial advantage with five weeks to go until the November 3 election.
The former vice president has held a modest but steady lead in national voter surveys for months, although opinion polls in the battleground states that traditionally decide elections show a closer contest.
On Wednesday Biden went on a whistle-stop train tour through the states of Ohio and Pennsylvania, concluding the day with remarks attacking Trump for his handling of the coronavirus pandemic.
Biden urged Americans to vote for him in large numbers to eliminate any possibility of Trump trying to stay in the White House if he lost the election.
Trump did not commit at the debate to accepting the election result, reasserting unfounded complaints that an increase in mail-in ballots because of the coronavirus pandemic would lead to widespread voting fraud.
"The president will step down. The American people will not stand for it. No agency would stand for that happening," Biden said on a campaign stop.
Also on Wednesday Trump attempted to distance himself from the right-wing "Proud Boys" group after declining to denounce white supremacists during the debate.
Trump had said the Proud Boys should 'stand back and stand by', before switching to an attack on the Antifa leftist group,
"I don't know who the Proud Boys are. I mean, you'll have to give me a definition, because I really don't know who they are. I can only say they have to stand down, let law enforcement do their work," he told reporters at the White House on the following day.
The Trump campaign accused the organisation of "moving the goalposts and changing the rules in the middle of the game."
Trump also was critical of the debate's moderator, Fox News anchor Chris Wallace, who spent much of the debate trying to restore order.
"Chris had a tough night," Trump posted on Twitter, calling the debate a "two on one" fight.
Biden said on Wednesday he hoped organisers of future debates would be able to turn off the microphone of the candidate who is not speaking.
"It was a national embarrassment," Biden said of the debate and Trump's performance. "I am not going to speculate what happens at the second or third debate."
The debate commission defended Wallace, thanking him "for the professionalism and skill he brought to last night's debate" and promising "additional tools to maintain order."
An estimated 73.1 million people tuned in to the face-off on Tuesday night across 16 networks, down from the 84 million who watched the first debate between Trump and Democratic rival Hillary Clinton in 2016.