Speaking to the former Fox News personality Tucker Carlson, Sen. J.D. Vance, the Ohio Republican and the party's vice presidential nominee, said one of his big worries is the bond market.

"The thing I really worry about on bond markets is, OK, we have $1.6 trillion to $2 trillion in debt every single year in this country getting added to the national debt. And the only thing that makes that serviceable is that interest rates are still pretty low," said Vance.

"If interest rates go to 8%, and you're spending way more to service the debt than you are on actual goods, services and infrastructure for your country, like that can become a huge spiral that could take down the finances of this country," he said.