The bank Mr. Varnell was said to target — the downtown branch of BancFirst, Oklahoma’s largest state-chartered bank — is about a half-mile from the site of that attack.

During a meeting in June with an undercover F.B.I. agent posing as someone who could help him, Mr. Varnell said that he wanted to start the next revolution and that he identified with what is known as 3 percenter ideology, according to an affidavit filed in support of the federal criminal complaint against him. Mr. Varnell sought to form and arm a small militia group, inspired in part by the movie “Fight Club,” the authorities said.

“I’m out for blood,” Mr. Varnell wrote in one text message to a confidential informant who cooperated with the authorities, according to the affidavit, which was written by an F.B.I. special agent. “When militias start getting formed I’m going after government officials when I have a team,” he wrote. The complaint did not name the informant.

In another text message, Mr. Varnell wrote: “I think I’m going to go with what the okc bomber used. Diesel and anhydrous ammonia.” He was referring to Timothy J. McVeigh, who was executed for the Oklahoma City bombing. Mr. McVeigh and a co-conspirator, Terry L. Nichols, built a giant fertilizer bomb using ammonium nitrate and racing fuel as their primary ingredients. Mr. Varnell later told the informant to get him ammonium nitrate, adding, “That’s all I need,” according to court documents.

Federal law enforcement officials said the public was not in danger at any time.

“There was never a concern that our community’s safety or security was at risk during this investigation,” Kathryn Peterson, the special agent in charge of the F.B.I. in Oklahoma, said in a statement. “I can assure the public, without hesitation, that we had Varnell’s actions monitored every step of the way.”