Some Republican officials, donors and advisers said Donald Trump, the Republican presidential candidate, had botched his debate with Democratic Vice President Kamala Harris, although Trump himself praised his performance.

"I think it was one of my better debates, maybe my best debate," Trump told the "Fox & Friends" program on Wednesday, adding that he was not sure whether to do another one. "I'd be less inclined ... because we had a great night."

Harris, 59, put Trump, 78, president from 2017-2021, on the defensive in a combative presidential debate on Tuesday with a stream of attacks on his fitness for office and his myriad legal woes. The election takes place on Nov. 5.

Republican Senator Lindsey Graham, a prominent Trump ally, was one of the few party leaders to publicly say Trump's performance was poor.

"A missed opportunity," Graham told reporters of Trump's debate performance, adding that the former president had failed to stay focused and lost chances to tout his record.

Chris Christie, a former Trump ally-turned-critic who ran against Trump for the 2024 Republican presidential nomination, said Harris was "exquisitely" prepared whereas Trump was not.

"Whoever did debate prep for Donald Trump should be fired. He was not good tonight at all," Christie, who helped Trump with debate preparation in the 2016 election cycle, said on ABC News.

The Trump campaign did not respond to a request for comment on whether there would be a shake-up of Trump's debate team.

With eight weeks to go before the election, and days until early voting starts in some states, the debate offered a rare head-to-head opportunity to face tens of millions of TV viewers.

Their ABC News debate attracted 67.1 million television viewers, according to Nielsen data, topping the roughly 51 million people who watched Trump debate then-candidate President Joe Biden in June.

The number does not capture the full extent of online viewing, which has grown in popularity as traditional TV audiences decline.

Six Republican donors and three Trump advisers, all but one asking to remain anonymous to speak freely, also told Reuters they thought Harris had won the debate largely because Trump was unable to stay on message.

Several brought up, with dismay, Trump's amplification of a false online claim that numerous Haitian immigrants in Springfield, Ohio, were eating residents' pets.

Two of Trump's advisers said they doubted the debate would move the needle in opinion polling.

In Reuters interviews with 10 undecided voters, six said after the debate they would now either vote for Trump or were leaning toward backing him. Three said they would now back Harris and one was still unsure how he would vote.

Still, in a sign of confidence in the debate's outcome, Harris' campaign challenged Trump to a second round in October.

Two of the six donors said they were not sure whether Trump should debate her again, with one saying it would hinge on whether his handlers were confident he could be more focused in a second round. Two other donors, however, said they thought Trump needed a second debate in order to regain momentum.

"My honest opinion is that Trump underperformed and she overperformed," said donor Bill Bean, a commercial real estate investor in Fort Wayne, Indiana. On the prospect of a second debate, Bean said: "I'd like to see one."