Fast food executive and former Labor Secretary nominee Andy Puzder said that opposition groups threatened his family during the confirmation process.

Puzder, who withdrew his nomination on the eve of his Senate hearing, told radio host Hugh Hewitt on Monday morning that he and his wife were subjected to serious threats after President Trump tapped him to lead the Department of Labor in December.

Puzder said he received packages and letters that went beyond typical hate mail or opposition post cards distributed by left-wing groups and unions. A hazmat crew and FBI officials arrived at his Franklin, Tennessee home to retrieve and analyze a package containing white powder that his wife had opened, he said.

"There was an envelope left at our house addressed to my wife that had white powder in it, a pink piece of paper with ‘Trump' written on it, and then obviously the white powder was in a plastic bag, but you open the envelope and a little powder came out," Puzder said. "We had an FBI terrorist team come to the house. We had a couple fire engines with hazmat teams come to the neighborhood."

An FBI spokesman from the Nashville-based Joint Terrorism Task Force said the agency does not comment on such incidents and could neither confirm or deny that the incident took place. A person familiar with the incident said it took place at Puzder's home on January 17.

Puzder is CEO of CKE Restaurants, the parent company of Hardees and Carl's Jr. He was the first career businessman nominated to the Department of Labor since 1981. Puzder said he withdrew after it became clear that he might not have the votes needed for confirmation, but he acknowledged that "the pressure on my family was really pretty tremendous."

Activists from Fight for $15, a protest movement backed by Service Employees International Union, demonstrated at Puzder's front door. His wife opened another package containing a noose, though Puzder did not witness that incident.

"I didn't see it, but I was told there was a paper-doll with a noose around its neck and there was—again, addressed to my wife, not addressed to me, which shows the cowardice of these people," Puzder said.

SEIU did not respond to a request seeking comment about whether the union condemned such behavior.

Despite threats to his family and company—organized labor filed more than 30 unfair labor practice complaints against CKE franchisees after the nomination—Puzder said his family supported him throughout the process. He said his wife urged him to move forward with the nomination.

"All of that [behavior] obviously intended to intimidate my family," Puzder said. "I actually said ‘look this is too much pressure on everybody. I think I should just withdraw my nomination' and she [his wife] said, ‘What, and let the bad guys win?.' She was very, very supportive."

One day after Puzder dropped out, Trump nominated Alexander Acosta, a former member of the National Labor Relations Board and dean of Florida International University's law school, for labor secretary. Acosta has since received endorsements from several major labor unions, though some groups, including SEIU, have promised to protest the nomination.