The man who broke into the San Francisco home of Nancy Pelosi two years ago and bludgeoned her husband with a hammer was sentenced on Friday to 30 years in federal prison, with credit for time already served.

Ms. Pelosi was the speaker of the House and second in line to the presidency at the time of the attack, which raised fears of politically motivated violence in the run-up to the 2022 midterm elections.

The assailant, David DePape, was convicted in November 2023 on federal charges. He admitted on the witness stand during the trial that he had carried out the attack, as he had done before in interviews with the police and media outlets. But he said that he never intended to hurt Ms. Pelosi’s husband, Paul Pelosi.

Mr. DePape said his intrusion into the couple’s home in the affluent Pacific Heights neighborhood was part of a plot to kidnap Ms. Pelosi and interrogate her about a supposed corrupt conspiracy led by Ms. Pelosi and other prominent liberal figures.

He was convicted of two federal crimes: attempted kidnapping of a federal officer and assault on an immediate family member of a federal official.

Prosecutors asked the court to impose the statutory maximum sentences for each offense — 20 years for the kidnapping charge and 30 years for the assault charge. The court did so, but it denied the prosecutors’ request that ten years of those sentences be served consecutively, meaning Mr. DePape would have been imprisoned for a total of 40 years. Instead, the judge, Jacqueline Scott Corley, said the sentences would run concurrently.

The federal public defenders representing Mr. DePape had asked for a total sentence of 14 years.

Judge Corley said in court that she had taken into account Mr. DePape’s lack of a previous criminal record and his vulnerability to conspiracy theories. But she said the violence he committed was “completely gratuitous,” and she expressed concern that his violent invasion of a sitting lawmaker’s home, which she called unprecedented, might frighten people away from serving in public office.

Mr. DePape also faces separate state charges stemming from the attack, including attempted murder, assault with a deadly weapon and elder abuse. Jury selection for his state trial is scheduled to begin on May 22.

Before the sentence was announced, Christine Pelosi, a daughter of Nancy and Paul Pelosi, read statements to the court from her parents about the impact of the attack. Mr. Pelosi’s statement described the persistent physical effects of his injuries, the emotional trauma of the attack and the continuing threats to the couple, and said that his life “has been irrevocably changed.”

Nancy Pelosi’s statement noted that “our home remains a heartbreaking crime scene,” and Mr. Pelosi said they had not yet been able to fully remove the stains of his blood from the floor.

The defendant did not speak at the hearing.

Mr. DePape reflects the underbelly of American politics: a man driven by online conspiracy theories who seemed to embrace the rhetoric of many right-wing figures, who have used dehumanizing language for years to describe Ms. Pelosi and call her an enemy of the United States.

His lawyers mounted a narrow defense in the federal trial, arguing that Mr. DePape had targeted Ms. Pelosi not because she was a United States government official — a required element of the federal charges — but because he saw her as part of an elite Democratic cabal that was bent on destroying American freedom. Mr. DePape had a list of other targets who were not federal officials, including Hunter Biden, the president’s son; the actor Tom Hanks; George Soros, the billionaire philanthropist; and Gov. Gavin Newsom of California.

A Canadian citizen who moved to San Francisco in his 20s, Mr. DePape was a solitary figure who worked odd jobs and lived for a time under a tree in a park in Berkeley, Calif. At times he seemed immersed in the liberal counterculture scene of the Bay Area, experimenting with psychedelics and protesting against the war in Iraq.

His partner during that time was a locally known activist named Oxane Taub, with whom Mr. DePape had two children. Ms. Taub, known as Gypsy, served time in prison for the attempted abduction of a 14-year-old boy, among other crimes.

After their relationship dissolved, he became estranged from his children and fell deeper into isolation, immersing himself in conspiracy theories like Pizzagate and QAnon and becoming a supporter of Donald J. Trump.

Mr. DePape’s lawyers told the court that he had taken responsibility for his actions and that he had been manipulated both by Ms. Taub, who was often in the courtroom during the trial, and by the online world of conspiracy theories.

“His entire adult life was indelibly shaped and distorted by an abusive long-term relationship who exploited his innate vulnerabilities and immersed him in a world of extreme beliefs where reality is not reality,” the lawyers wrote in their memorandum requesting a lenient sentence. “He was further radicalized through his obsessive consumption of media amplifying extreme beliefs.”

Ms. Taub, who attended the sentencing on Friday, said she had sometimes been abusive to partners in the past, but never to Mr. DePape.

“It’s interesting how they use that word ‘radicalize’ as an insult,” said Ms. Taub, who described herself as a “professional conspiracy theorist.”

Prosecutors, by contrast, urged the judge to impose a “terrorism enhancement” to his sentence, saying his “actions were an attack themselves on democracy and our institutions.” “The defendant intended to make a statement,” they wrote. “He came prepared with the tools he needed to broadcast his hostage-taking to the world.”

In a statement read outside the courtroom by a spokesman after the hearing, Ismail Ramsey, the U.S. attorney for the Northern District of California, said that “today’s sentence is a stern reminder that political discourse must never transform into violence.”

Mr. DePape was 42 when he broke into the Pelosis’ house in the early hours of Oct. 28, 2022. Ms. Pelosi was in Washington at the time, but her husband, then 82, was asleep in their bedroom.

Mr. DePape told the police that he was on a mission to capture Ms. Pelosi, interrogate her and “break her kneecaps” if she lied to him. He said he planned to wear a unicorn costume while questioning Ms. Pelosi, and to broadcast video of the interrogation online.

Bursting into the couple’s bedroom, he said repeatedly, “Where’s Nancy?”

At the trial, Mr. Pelosi explained how he was able to surreptitiously call 911 from his bathroom. When the police arrived, Mr. Pelosi opened the door for them while he and Mr. DePape each had a hand on a large hammer that Mr. DePape had brought with him.

At that moment, Mr. DePape wrested the weapon free and struck Mr. Pelosi repeatedly in the head, knocking him to the floor in a pool of his own blood. Mr. Pelosi suffered two skull fractures and underwent surgery, spending six days in the hospital.