“You have to swear on a Bible to be an elected official in the United States of America,” Mr. Crockett said.

The CNN anchor Jake Tapper responded: “You don’t actually have to swear on a Christian Bible. You can swear on anything, really. I don’t know if you knew that.”

After some back and forth, Mr. Tapper reiterated: “The law is not that you have to swear on a Christian Bible. That is not the law. You didn’t know that?”

Mr. Crockett remained silent, his mouth gaping, for several seconds.

Oaths of office can be taken on a Hebrew Bible, or on a Quran, as Rep. Keith Ellison of Minnesota demonstrated in 2007 when he used one once owned by Thomas Jefferson to be sworn in as the first Muslim member of Congress.

Mr. Ellison, or anyone else, could have also used a comic book, a lesser Shakespeare play or nothing at all.