The government is seeking a 45-year prison term for the man who attacked the Washington, D.C., headquarters of the Family Research Council last year.
Floyd Corkins pleaded guilty Wednesday to assault with intent to kill and committing an act of terrorism. Sentencing is scheduled for April 29.
Corkins confessed he planned to kill as many people as possible at the conservative Christian lobbying group's headquarters.
He wounded FRC security guard Leo Johnson, who was still able to subdue him in the lobby.
"Although the defendant largely failed to bring about the violence he sought, he was still able to accomplish one of his objectives -- that is, to use acts of violence to terrorize and intimidate those within the District of Columbia and the United States who did not share his political beliefs and views," government attorneys wrote.
Corkins, who had been volunteering at a center for gay, lesbian and transgender people, was angry about the Family Research Council's opposition to gay marriage.
He told federal agents he intended to smear his victims' faces with Chick-fil-A sandwiches to make a statement against people who oppose gay rights.