Dr. Ben Carson. AP/Carolyn Kaster, File Dr. Ben Carson struggled to win over a skeptical radio host who repeatedly grilled him on Wednesday over national security issues.

Carson, a retired neurosurgeon and likely presidential candidate, faced off against conservative talk show host Hugh Hewitt. As the conversation began, Hewitt said he didn't want to conduct an "ambush interview." However, he nevertheless pressed Carson on specific military programs and even the origins of the Islamic faith.

"I want to be respectful in posing this. But I mean, you wouldn’t expect me to become a neurosurgeon in a couple of years. And I wouldn’t expect you to be able to access and understand and collate the information necessary to be a global strategist in a couple of years. Is it fair for people to worry that you just haven’t been in the world strategy long enough to be competent to imagine you in the Oval Office deciding these things?" Hewitt asked, according to a transcript of the show.

Carson, who polls show is a leading White House contender, insisted he had the breadth of knowledge necessary to be commander-in-chief. Nevertheless, Carson appeared to get tripped up by a few of Hewitt's questions.

At one point, Carson said the US should convince the three Baltic countries — Estonia, Lithuania, and Latvia — to join the North Atlantic Treaty Organization military alliance in order to counter Russian President Vladimir Putin. However, those countries joined NATO more than a decade ago, in 2004.

"We need to convince them to get involved in NATO and strengthen NATO," Carson said.

Hewitt, who will question the Republican presidential candidates at an official presidential debate, called Carson out.

"Well, the Baltics, they are in NATO," the radio host said. "Dr. Carson, one of the things I know that’s going to come up, and again, I don’t do ambush interviews, but ... it appeared you didn't know that the Baltic states were a part of NATO."

Radio host Hugh Hewitt. AP/Alex Gallardo

Hewitt said he had additional concerns about Carson dating tensions in the Islamic religion back to the time of Esau and Jacob, figures from the Bible's Old Testament. Hewitt noted Islam originated with the Prophet Muhammad, who was born several hundred years after the Old Testament.

"Well, first of all, you have to recognize they go back thousands and thousands of years, really back to the battle between Jacob and Esau," Carson said when asked about the source of jihadist "rage."

Hewitt again called out Carson.

"Dr. Carson, but you know, Muhammad lives in 632AD, so it’s a 1,300, 1,400 year old religion. How do you go back to Jacob and Esau, which are BC?" he asked.

Carson repeated his statement as Hewitt told him "scholars might dispute" that claim.

Hewitt also drilled down to a level of specificity on Defense Department programs he suggested Carson might be uncomfortable with, including "upgrading our nuclear triad, specifically our submarine fleet," the number of Ohio-class submarines the US should have, and the Overseas Contingency Operations fund.

"There will be a lot of important questions which are detailed," Hewitt added. "For example, should we buy more F-18 Super Hornets, because the F-35's aren’t in production at the level that we want? Are those fair game to ask Ben Carson, who's a neurosurgeon and new to the national defense? Or are those off limits?"

Carson replied by saying he would not "micromanage" the Pentagon's budget.

"They're fair questions to ask," he said. "And the answer to that kind of thing is the job of the commander-in-chief is not to micromanage the military budget or micromanage the way that things are done."

Watch the full interview below or click here for the full transcript.