WASHINGTON — Declaring that the central cause of the Jan. 6, 2021, attack on the Capitol was “one man,” the House committee investigating the assault delivered its final report on Thursday, describing in extensive detail how former President Donald J. Trump had carried out what it called “a multipart plan to overturn the 2020 presidential election” and offering recommendations for steps to assure nothing like it could happen again.

It revealed new evidence about Mr. Trump’s conduct, and recommended that Congress consider whether to bar Mr. Trump and his allies from holding office in the future under the 14th Amendment’s ban on insurrectionists.

“The central cause of Jan. 6 was one man, former President Donald Trump, whom many others followed,” the report said. “None of the events of Jan. 6 would have happened without him.”

The release of the full report was the culmination of the panel’s 18-month inquiry and came three days after the committee voted to formally accuse Mr. Trump of inciting insurrection, conspiracy to defraud the United States, obstruction of an act of Congress and one other federal crime as it referred him to the Justice Department for potential prosecution. While the referrals do not compel federal prosecutors to take any action, they sent a powerful signal that a select committee of Congress believes the former president committed crimes.

“Our institutions are only strong when those who hold office are faithful to our Constitution,” Representative Liz Cheney, Republican of Wyoming and the vice chairwoman of the committee, wrote in the report, adding: “Part of the tragedy of Jan. 6 is the conduct of those who knew that what happened was profoundly wrong, but nevertheless tried to downplay it, minimize it or defend those responsible.”