Indeed, the leading complaint from some of Trump’s top allies after the opening debate was not the perceived unfairness of moderator Chris Wallace — though they took repeated issues with the Fox News anchor’s performance — or Biden's evasive answer to a question related to the Supreme Court, but the president’s own demeanor. Overcome with scorn for Biden, Trump jabbed and jeered his way through the night without ever giving his opponent a chance to self-implode. The strategy confounded supporters who had giddily approached the first debate thinking it would be a prime opportunity for voters to see the 77-year-old Democratic presidential nominee stumble through answers with rambling responses and cringe-worthy gaffes.

One Trump adviser had flashbacks to the O.J. Simpson trial, likening Trump to the football legend’s domineering defense attorney Barry Scheck and Biden to frazzled prosecutor Marcia Clark. But while Scheck may have “brilliantly” saved his client with merciless cross-examinations, the adviser said Trump’s attempts to corner Biden only further imperiled his unstable campaign.

Another person involved with the president’s campaign said they couldn’t blame anyone who turned the TV off halfway through the debate: “The few independents that we need, I imagine some of them just flipped the channel after the first hour.”

Others were more blunt.

“It was really frustrating to watch,” said Dallas investor Doug Deason, a GOP megadonor and Trump supporter. “He’s the president of the United States. He should have not let it get out of hand like it did and instead he led it.”

Deason was invited by the Republican National Committee to watch the debate at the Trump International Hotel in Washington, where dozens of MAGA fans spent Tuesday night sipping cocktails and watching the ugly contest unfold. He declined the invitation, but assumed many of those who attended shared his frustrations as they took in the debate from a gilded ballroom blocks away from the White House.

“The whole thing was just so cringeworthy,” he said. “They’re blaming Biden, but they’re not happy with Trump. The president should have sat back and let Biden just talk himself into circles, but instead he kept interrupting.”

“He saved Biden’s day by doing that,” Deason added. “It was a huge misstep.”

Between now and Oct. 15, when Trump and Biden are scheduled to face off for the second time in Miami, some Trump supporters said they want the president’s demeanor to undergo a wholesale makeover. Instead of constant interference, they want brief interruptions to introduce topics left untouched by the moderator or to pose open-ended questions to Biden. Rather than juvenile insults, they want the witty one-liners that defined Trump’s performances in the 2016 GOP primary debates.

Barring a course-correction in the second debate, they said the president could permanently jeopardize his campaign’s effort to win over undecided voters and reverse his eroding support with women.

“He needs to show a little more of his charm and humor, less anger,” said Seth Weathers, former director of Trump's Georgia campaign and co-founder of a conservative apparel business.

“More quips, less hits,” Weathers added.

The cast of “Fox & Friends,” a Fox News morning show Trump watches religiously, on Wednesday morning aired a rare segment in which several conservatives close to the Trump campaign also grumbled about the president’s debate performance.

“The president interrupted way too much. Mr. President, please don’t do that in the next debate,” said former Trump campaign adviser Stephen Moore.

In the same segment, Ari Fleischer, a White House press secretary under President George W. Bush, urged Trump to “interrupt less” and “let Biden flail" next time.

The person involved in Trump’s reelection effort said the president ruined several moments during the Cleveland debate when Biden appeared to be on the brink of delivering an unsatisfactory answer, but was interrupted by Trump before he could complete his sentence.

This person cited Biden’s response to Wallace when he asked if the former vice president, who has billed himself as a “transition candidate,” would support the “Green New Deal” climate plan championed by progressives. Biden, whose campaign website describes the multitrillion dollar proposal as a “crucial framework for meeting the climate challenges we face,” distanced himself from the deal — that is, until Trump jumped in to suggest his opponent had “just lost the radical left.”

“It was one of those things where you just kind of wanted him to finish his thought. I was like, ‘You’ve got him cornered, just let him finish it,’” said the person involved in Trump’s reelection.

Weathers said Trump should have refused to discuss other topics until the former vice president definitively said he would support or oppose court-packing if elected.

“Are you willing to tell the American people tonight whether or not you will support either ending the filibuster or packing the courts?” Wallace suggested, referring to a scenario floated by some progressive activists in which Democrats could add more justices to the Supreme Court bench to erase its conservative tilt.

“Whatever position I take on that, that will become the issue. The issue is the American people should speak. ... Vote and let your senators know how strongly you feel,” Biden responded.

Before Wallace could pose a follow-up, Trump cocked his head toward Biden and pounced: “Are you going to pack the court? Are you going to pack the court? He doesn’t want to answer the question.”

“Who is on your list, Joe?” Trump continued, referring to Biden’s yet-to-be-released names of potential Supreme Court nominees.

The president “could have done something more theatrical than what he did” instead of repeatedly interrupting Biden on the court-packing question, said the Trump campaign adviser. “It is outside the mainstream of America to support packing the court and for a presidential candidate to say, ‘No, I’m not going to answer that question,’ I just think the president should have had a more succinct response ready to go.”

The format of the next debate is likely to reduce bickering between Trump and Biden — directing their focus toward audience questions in a town hall-style format as opposed to simply responding to the moderator and each other — though it is unclear if the president and those involved in his debate preparations are eyeing a different approach.

While former New Jersey Gov. Chris Christie, who has spent the past few weeks in debate preparation with Trump, admitted he was “too hot” on the debate stage, the president himself seemed pleased with his performance. AFter the debate, Trump lit up his Twitter feed with retweets of people who praised his combative style and suggested in a Wednesday afternoon tweet that the disorder that ensued the previous night had nothing to do with his conduct.

“Try getting a new Anchor and a smarter Democrat candidate!” Trump tweeted in response to a statement from the Commission on Presidential Debates promising to add new “tools to maintain order” in the remaining verbal contests.

“President Trump controlled the entire conversation … and kept Joe Biden on his heels and looking weak and unable to defend his 47 years of failure in Washington,” said Trump campaign communications director Tim Murtaugh. “We are enthusiastic about the upcoming debates and look forward to them.”