FBI officials said they have arrested a 27-year-old suspected white supremacist who was allegedly planning a bombing at a Colorado synagogue.

The suspect, identified as Richard Holzer, was allegedly planning to target Temple Emanuel in Pueblo, which is the state's second-oldest synagogue, the FBI said Monday. Holzer is charged with attempting to obstruct religious exercise by force using explosives and fire.

He allegedly told an undercover FBI agent that he hoped to poison members of the synagogue and claimed he had paid off a "Mexican cook to hex and poison" attendees by putting arsenic in the water pipes, according to an arrest affidavit.

The undercover agent connected with Holzer through a Facebook account that portrayed her as a white female who is supportive of white supremacy ideology. Holzer allegedly told her that he was "a skinhead" and former member of the Ku Klux Klan and sent her images of himself wearing clothing that featured symbols related to white supremacy.

The FBI said the account was one of several that Holzer allegedly used to "promote white supremacy ideology" and racially-motivated acts of violence. At one point, he posted in a group chat: "I wish the holocaust really did happen… they need to die.”

In one exchange on Oct. 3, Holzer said he was getting ready for a racial holy war and said he was going to Temple Emmanuel in Pueblo “to scope it out.” Holzer eventually met with an undercover FBI agent to discuss his hatred of Jewish people and explain his plan to poison the Pueblo synagogue with arsenic.

Court documents say Holzer first suggested the idea to attack the synagogue with Molotov cocktails, but later decided he’d need something stronger. The agents told Holzer they could obtain pipe bombs and dynamite from out of state. On Oct. 31, he told the undercover agents he planned to go through with the attack on Nov. 1. According to the affidavit, Holzer “said that he wanted to put the Synagogue on the ground and demolish it.”

On Nov. 1, Holzer met three undercover FBI agents at a hotel. They showed him pipe bombs and dynamite. That is when he was arrested, at which point Holzer allegedly waived his Miranda rights and confessed.

When asked what he would have done if someone had been inside the synagogue during the bombing, he allegedly said he would have gone through with the attack because anyone inside would be Jewish.

Michael Atlas-Acuna, the president of Temple Emanuel, said he was unaware of the plot until reporters started calling him. He said he received a call from the FBI in Colorado Springs on Monday morning, saying they wanted to meet with him but they did not say what it was regarding. He told ABC News that he thought it was a prank call at first, but realized that it was serious after dialing back the number.

Atlas-Acuna said the synagogue has a security plan in place for these types of events.

"We take our security very seriously here. We have been since what happened in Pittsburgh ... we're not going to be victimized and we're going to defend ourselves," Atlas-Acuna said in an interview Monday. "I've never been naive to think that it couldn't happen to us because there's been other things that have happened in small communities like shooting churches, so I've never been that naive."

"I think that all Jewish communities have to continue to protect themselves. Make sure they have armed guards, make sure they have security. We don't like the idea that America that we have to deal with this, but again, it's just a reality of where we live right now," he added.

ABC News' Becky Perlow contributed to this report.