As the House of Representatives opened the floor on Thursday to debate the fate of George Santos, Republican of New York, the arguments over whether to expel him took an immediate and indecorous turn.

Mr. Santos’s use of Botox was invoked several times, even by those defending him. His detractors pointed to falsified ties to the Holocaust and to his claims, contradicted by paperwork, that his mother was at the World Trade Center on Sept. 11. The final speaker calling to expel Mr. Santos concluded with the briefest of remarks: “You, sir, are a crook.”

The dramatic floor debate was, perhaps, a fitting culmination to a political career that has been defined by spectacle, scandal and lies.

All that could come to an end on Friday, when the House is scheduled to vote on a resolution to expel Mr. Santos, 35, following the release of a damning and detailed report from the House Ethics Committee that found “substantial evidence” that he had violated federal law.

Mr. Santos offered a minimal defense, again refusing to provide evidence that would counter the laundry list of misdeeds and 23 criminal charges that Republicans and Democrats cited to support his removal.

Instead, as a group of lawmakers repeatedly cited the findings of the ethics report, Mr. Santos and his defenders argued that removing him before his criminal case is resolved could open the floodgates to a raft of frivolous expulsion efforts, overriding the will of voters.

“The expulsion of George Santos would set a new precedent,” Representative Matt Gaetz of Florida said, adding: “The problem is, it’s a lower standard for due process, without merit.”

But Mr. Santos’s critics, most of them members of his own party, argued that the congressman had been given ample opportunity to defend himself, including during the months in which the Ethics Committee was investigating him. Its report was conclusive, they said.

“I ask my colleagues: If we do not take the Ethics Committee and their results seriously, then why even have the committee in the first place?” Representative Anthony D’Esposito of New York said.

Friday’s vote on Mr. Santos’s fate will be the third time the House has confronted the issue this year.

Whether the outcome will be different this time remains unclear. Expelling a representative requires a two-thirds majority, a threshold that the previous efforts failed to meet. But since the ethics report was released, a number of lawmakers who previously opposed expulsion have publicly changed their views.

Mr. Santos himself has said that he expected to be removed from office, a view he reiterated on Thursday. But even as he insisted he would be “at peace” with an eventual decision to expel him, he has refused to resign, a characteristic defiance that set the stage for Thursday’s circuslike debate.

Complicating the landscape for Republicans is the stance of Speaker Mike Johnson, who has expressed reservations about expelling Mr. Santos, but refrained from mounting a formal effort to protect him.

Infighting between Republicans was on full display during the debate, at one point descending into name calling when Representative Max Miller of Ohio used his few seconds of time to address Mr. Santos directly, calling him a crook.

Mr. Santos shot back by referring to accusations of physical abuse that Mr. Miller has denied, saying Mr. Miller was “accused of being a woman beater.”

The lawmakers who favored expelling Mr. Santos largely used their time to repeat the numerous allegations against him. Representative Michael Lawler, a Republican representing the lower Hudson Valley, chose to recall Mr. Santos’s false claims of associations with 9/11 and the Holocaust, castigating his colleague for using “tragic events in history to try to propel himself to public office.”

In an unusual turn, the Republican chairman of the Ethics Committee, Michael Guest of Mississippi, spoke in his personal capacity to give a passionate defense of the committee’s report.

Armed with large posters printed with some of the report’s findings, Mr. Guest noted that Mr. Santos had previously said that he “looked forward to seeing the Ethics process play out.”

Mr. Guest, who introduced the current resolution to expel Mr. Santos, said that the process had been completed after months of investigation, concluding with a plea that. “all members vote to support the expulsion of Representative Santos.”

Mr. Santos spent much of his time casting aspersions on the committee. He accused it of rushing to oust him without giving him due process and asserted that the bipartisan Ethics Committee started its work with a predetermined outcome.

“I’m not trying to be arrogant or spiteful or, you know, disrespectful of the committee,” Mr. Santos said. “But I am curious to know: What is the schedule of the Ethics Committee? Why rush this?”

Many of the Republicans who rose to support Mr. Santos during Thursday’s debate also framed the decision to expel him as an important question of precedent.

Only five members of the House have ever been removed. Three of them were expelled for supporting the Confederacy during the Civil War. Two others, one in 1980 and one in 2002, were removed from office after criminal convictions.

Representative Clay Higgins, Republican of Louisiana, said that expelling Mr. Santos would override the will of voters.

“Are the American people to believe that the opinions of congressmen is a higher standard than the deliberate vote of the American people?” asked Mr. Higgins, who voted to overturn the results of the 2020 election.

He added that lawmakers’ push to expel Mr. Santos was “like witnessing an otherwise fair and compassionate village gather to celebrate the burning of an alleged witch.”

Still, some of the Republicans who rose to oppose Mr. Santos’s expulsion made clear that they did not back his behavior.

Even as he was speaking on Mr. Santos’s behalf, Mr. Gaetz brought up some of the salacious claims in the ethics report: that Mr. Santos used campaign funds to pay for Botox and purchases on OnlyFans, a website known for explicit content.

At the start of his speech, he also sought to distance himself from his colleague. “I rise, not to defend George Santos, whoever he is,” Mr. Gaetz said, eliciting chuckles from those in the House chamber.

Mr. Santos’s behavior on Thursday was in many ways a summation of his 11 months on the Hill. He vacillated between appearing calm and defiant, occasionally making jokes but rarely sounding contrite.

At the start of the day, he held a news conference in which he blasted his colleagues and argued that the expulsion vote was “theater for the American people at the expense of the American people.”

Later, away from cameras, he told a group of reporters he was “oddly calm” and had started to think of his future. He planned to write a book, he said, and had not ruled out appearing someday on a television show like “Dancing With the Stars.”

At the end of the debate, he seemed to acknowledge that his remarks would have little influence on the outcome of Friday’s vote.

“If tomorrow, when this vote is on the floor, it is in the conscience of all of my colleagues that they believe that this is the correct thing to do, so be it. Take the vote,” Mr. Santos said. “I’m at peace.”

Reporting was contributed by Luke Broadwater and Annie Karni from Washington, and Nicholas Fandos from New York.