A 42-year-old man accused of attacking US House Speaker Nancy Pelosi's husband last week has been charged by federal prosecutors with assault and attempted kidnapping, the US Justice Department says.
David DePape, 42, is accused of breaking into the Pelosis' San Francisco residence early on Friday and assaulting Paul Pelosi, 82.
The two counts DePape faces carry up to 50 years in prison, the department said.
Paul Pelosi underwent surgery for a skull fracture and injuries to his hands and right arm although doctors expect a full recovery, according to Nancy Pelosi's office.
The incident stoked fears about political violence ahead of midterm elections on November 8 that will decide control of the House of Representatives and Senate during one of the most vitriolic and polarised US campaigns in decades.
Early on Friday, police were dispatched for a "well-being" check on the basis of a cryptic emergency-911 call from the residence, police said.
Officers arrived at the front door and saw DePape and Pelosi struggling over a hammer.
As the officers shouted at both men to drop the tool, DePape yanked the hammer away and struck Pelosi at least once.
The officers then tackled, disarmed and arrested DePape, San Francisco Police Chief William Scott said.
The San Francisco Police Department recovered zip ties in Pelosi's bedroom and in the hallway near the front door of the residence.
Police also found a roll of tape, white rope, a hammer, one pair of rubber and cloth gloves and a journal in DePape's backpack, the Justice Department said.
Scott said hours after the attack that it was not a random act of violence.
The intruder shouted, "Where is Nancy?" before attacking, according to a person briefed on the incident.
The 82-year-old House Speaker herself, a Democrat who is second in the line of succession to the US presidency, was in Washington DC at the time.
She flew to San Francisco to be with her husband and released a statement on Saturday expressing dismay that "a violent man broke into our family home, demanded to confront me and brutally attacked my husband Paul".
After he was arrested at the house, DePape was taken to a San Francisco hospital but it was not made clear whether he was there for medical or psychiatric care, or both.