A US federal jury on Thursday convicted a right-wing conspiracy theorist of a hammer attack on the husband of former US House Speaker Nancy Pelosi, prosecutors said.

David Wayne DePape, 43, broke into the Pelosis' San Francisco home and struck Paul Pelosi over the head with a hammer in the early morning hours of October 28, 2022, while Nancy Pelosi, a Democrat, was still speaker and away in Washington.

The San Francisco jury, which had deliberated since midday on Wednesday, found him guilty of attempted kidnapping and assault of an immediate family member of a federal official, a spokesperson for the US Attorney's office said.

The crimes carry potential prison sentences of 20 years and 30 years, respectively, under federal sentencing guidelines.

DePape also faces further charges including attempted murder in California state court that carry a potential sentence of 13 years to life in prison.

Nancy Pelosi issued a statement on behalf of her family thanking people for their support and saying Paul Pelosi continues to make progress on his recovery, but withheld comment on legal matters because the state case was still pending.

"The Pelosi family is very proud of their Pop, who demonstrated extraordinary composure and courage on the night of the attack a year ago and in the courtroom this week," the statement said.

Defence attorney Jodi Linker argued during the trial that DePape did not commit a federal crime because he was not driven by Pelosi's official duties as speaker.

Instead, she argued, DePape's firm belief in wide-ranging but misguided conspiracy theories motivated him to bring down the wealthy and powerful ruling class.

Linker let many of the facts of the case go uncontested as the hammer strike was recorded by police body cameras and DePape admitted to his actions while testifying in his own defence. (Reuters)