Before serving in President Donald Trump's Cabinet and as a US congressman, Zinke interviewed fellow former Navy SEAL and political activist Larry Bailey on "Commander Z," Zinke's Montana radio show that aired on the Military Appreciation Channel. Bailey, a co-founder of the anti-Obama group Special Operations Speaks, described himself in 2012 as a birther and said, falsely, that Obama wasn't born in the United States.

The interview with Bailey and two other radio appearances reviewed by CNN's KFile show Zinke engaging with and promoting fringe, conspiratorial views.

In a statement to CNN, Interior Department spokeswoman Heather Swift said, "As a radio host, (Zinke) had many guests on his program who expressed a variety of views and opinions. Mr. Zinke would always challenge his guests to defend their opinions regardless of the topic and no matter how controversial."

In the July 2013 interview , Zinke said to Bailey, "You took on birther, college, you're pretty hard on this administration."

Bailey said that admitting he was a birther led to him losing donors to his group because people don't want to be perceived as being against Obama because of his race.

Zinke then said, "And the college records, you know, why not release them? I'm interested. Did he [Obama] say he was a foreigner and did he get a scholarship? Did he apply and receive a grant? That's what I hear. I don't know."

Bailey then claimed without evidence that a black Muslim man arranged for Obama to get admitted to Harvard Law School and that he paid for schooling with a grant from the Saudis.

"I'd like to see his transcripts. I'd like it definitive," Zinke responded.

"I hear things, you read things, you know, and obviously they're -- if our national PRISM program is out in the wire you, you'd think that we could get a hold of our president's college transcripts, but maybe that's just a bridge too far," Zinke continued, referencing the NSA surveillance program.

Far-right activists questioned Obama's citizenship and the veracity of his birth certificate dating back to when he was a candidate in the 2008 presidential race. Obama released his long-form birth certificate in 2011 showing he was, in fact, born in Hawaii.

Trump was one of the leading voices of the movement. During the 2016 election, Trump admitted that Obama was born in the US.

Radio ruminations about Michelle Obama and Ted Cruz

In another radio interview in April 2013, Zinke discussed a conspiracy theory about the Boston bombing terrorist attacks that alleged a third person, a Saudi national, was involved in the attack. The theory is based off news reports at the time of the bombing that a Saudi national injured in the bombing was being investigated as a "person of interest," but was later clarified that he was just a witness.

"On this, if Michelle Obama, if the first lady is involved at all, I mean, visiting any capacity. I mean, if that is true. This is, I'm flabbergasted, I'm flabbergasted," Zinke responded, noting that many of 9/11 hijackers were Saudi.

"I don't blame every Saudi," Zinke continued. "I have a lot of friends as you do that, that are Saudi, but certainly we can't let our guard down. I don't think that these two individuals were operating alone. I think it smacks of a cell. And we've talked about a cell. We looked at it, we've hunted cells before. This has every trace, every, you know, evidence leading towards a cell. I'm hoping the Saudis aren't involved. Uh, but, but the facts are as they are."

In March 2016, Zinke, then a US congressman representing Montana, appeared on "Where's Obama's Birth Certificate" radio show , a prominent platform in the birther community. As a congressman, Zinke was the highest-ranking US government official or representative to appear on the show and the only congressman to ever appear on the show.

In Zinke's appearance, the topic of discussion was Texas Sen. Ted Cruz's Canadian birth, which at the time was an issue in the 2016 Republican presidential primary campaign. Zinke said then-candidate Donald Trump had a good point that Cruz might not be eligible to run for president.

"I think he does have a point," Zinke said. "Now, I think Ted Cruz is one of the brightest people I've ever been around...Not born, not being born in the USA, you know, that's an issue because you look at OK, if, if the bar now is your mother is a US citizen. Well, historically Churchill, the King of Jordan, I know a number of Saudi princes, it opens up Pandora's Box. And so I think Donald Trump has a point and I do think it would have to be adjudicated at a higher level. This is not to say that Ted Cruz is not capable of being the president as far as his capability goes."