“My feelings were that we were going to have civil unrest because there was so much going on with Obama,” Mr. Morgan said. He believed that people were going to rise up against the attempts to overhaul health care and restrict guns, and that societal collapse would soon follow. He envisioned “roving bands of gangs” hunting for food and necessities in the aftermath. He bought riot gear, bulletproof vests and a small arsenal of firearms, so that “if you had to engage a band of marauders, you would have a chance to save your family.”

The keystone of his survival plan was what lay underneath: a shelter 26 feet underground, beneath a 39-inch solid ceiling. It contains 2,000 square feet of bedrooms and common space along with a stocked food pantry, an air filtration system and two escape tunnels, one of them 100 feet long. The company that installed the shelter suggested that Mr. Morgan keep quiet about it, because “if anything ever happened, there’d be people that try to take the bunker.”

Mr. Morgan quickly considered his other guns — another pistol in the drawer, the 12-gauge shotgun in the closet, the AR-15 in the guest bedroom — but saw his cellphone on the nightstand. He grabbed it and called the police. “See, that’s another thing I hate myself for,” he said. If he had just gotten another gun, he could have killed the intruder there and then.

He instead speculated about political forces that might have it in for him and his family. He talked about hired assassins and past C.I.A. experiments with brainwashing, and suggested that a violent attack on the home of a Second Amendment champion like himself had all the signs of an operation to justify more gun control. “I just think that I was chosen to be a false flag,” he said. This made a lot more sense to him than murdering a family to get to their bunker. Still, he could not shake the thought that his decision to enter politics had been his fatal error. If he had kept out of public life, neither his politics nor his bunker would have been so widely known.