Gregory Giusti, 49, entered a guilty plea to one count of intending to impede and intimidate a U.S. official by threatening the official's immediate family. The threat occurred during a March 25 phone call.
Giusti admitted during the plea before U.S. District Judge Jeffrey White that he had threatened Pelosi, D-San Francisco, during the call, saying that if she voted for certain legislation, she wouldn't have "a home to come home to" in California.
Earlier court documents indicate Giusti was referring to the health care reform bill.
Giusti also admitted during the plea to making more than 30 interstate threatening calls in February and March from his San Francisco apartment to Pelosi's Washington, D.C., office and home.
Giusti, who is being held without bail, will be sentenced by White on Dec. 2. Under the plea agreement, prosecutors and defense attorneys are recommending a sentence of one year and nine months in prison.
But White has the power to reject the sentence, in which case Giusti would have the right to withdraw the plea. The charge carries a possible maximum sentence of six years in prison.
Giusti's attorney, Elizabeth Falk, said at the start of the hearing that he has been diagnosed with Asperger's syndrome, a mild form of autism.
She said the disorder doesn't affect Giusti's intelligence or "ability to understand what's happening," but does affect his ability to sympathize with others.
"I do believe he meets the definition of competency. He is aware of what's going on Thursday," Falk told White.
The judge questioned Giusti extensively during the hearing about whether he understood the plea and the rights he was giving up.
Giusti, dressed in Alameda County Jail clothing, answered most questions with a clear "I do," or "Yes, sir," but choked up and wept quietly several times.
White said he concluded that Giusti was competent to enter the plea.
Joseph Cotchett, a lawyer representing Pelosi, said the Congresswoman supports the plea agreement and is not seeking financial restitution.