The man who clubbed US House Speaker Nancy Pelosi’s husband in the head with a hammer after forcing his way into the couple’s San Francisco home has faced charges of attempted murder and other felonies.

Police initially declined to offer a motive for Friday’s assault on Paul Pelosi, 82, who according to his wife’s office underwent surgery for a skull fracture and injuries to his right arm and hands, though doctors expect a full recovery.

But the incident stoked fears about political violence less than two weeks ahead of midterm elections on November 8 that will decide control of the House of Representatives and Senate, coming amid the most vitriolic and polarised US political climate in decades.

The 82-year-old House speaker herself, a Democrat who is second in the constitutional line of succession to the presidency, was in Washington at the time of the assault.

She flew to San Francisco to be with her husband. Three dark-coloured SUVs believed to belong to a special security detail were parked on Saturday with a city police patrol car outside Zuckerberg San Francisco General Hospital, where Paul Pelosi was admitted.

Paul Pelosi Jr, the couple’s son, was also at the hospital. Asked by a reporter for an update on his father, he replied, “So far, so good.”

President Joe Biden, speaking to reporters in Wilmington, Delaware, on Saturday, said he understood Pelosi’s husband “seems to be doing a lot better,” and that the attack appeared to have been “intended for Nancy.”

Police identified the man arrested at the scene as David DePape, 42. He, too, was taken to a San Francisco hospital.

Online sheriff’s records showed he was booked into custody on suspicion of attempted murder, assault with a deadly weapon, elder abuse, battery, burglary, and several other felonies.

Formal charges will be filed on Monday, and his arraignment is expected on Tuesday, according to the San Francisco district attorney’s office.

San Francisco Police Chief William Scott told a Friday night news briefing that police detectives, assisted by FBI agents, had yet to determine what precipitated the home invasion but said, “We know this was not a random act.”

A statement from Nancy Pelosi’s spokesman, Drew Hammill, said Pelosi’s husband had been attacked “by an assailant who acted with force, and threatened his life while demanding to see the Speaker.”

The intruder shouted, “Where is Nancy?” before attacking, according to a person briefed on the incident who spoke to Reuters on condition of anonymity.

In recent posts on several websites, an internet user named “daviddepape” expressed support for former president Donald Trump and embraced the cult-like conspiracy theory QAnon. The posts included references to “satanic pedophilia,” anti-Semitic tropes and criticism of women, transgender people and censorship by tech companies.

The incident came a day after New York City police warned that extremists could target politicians, political events and polling sites ahead of the midterms.

The US Capitol Police said they investigated 9625 threats against lawmakers from both parties in 2021, a near threefold increase from 2017.

– AAP