McCaskill raised the possibility that foreign entities holding Trump's debt could attempt to influence policy through his business ties.
"The American people want to know how much debt is owed by the Trump businesses to foreign entities because that could have a direct impact on our national security," said McCaskill.
"Isn't is true that a lot of his debt is held by foreign interests?" asked McCaskill.
"I don't know, I've just read it in the papers," replied Mnuchin.
"Don't you think you should know that as someone who runs the Committee on Foreign Investments if we're talking about the commander-in-chief?" asked McCaskill. "Should you as the Secretary of the Treasury know what percentage of his debt — I am told by people who are familiar with this business that it is a huge percentage of his debt — that is held by foreign interests?"
"If I am confirmed I will assure you that the requirements of the Constitution are upheld and I think you have a valid point about foreign debt and understanding foreign things," said Mnuchin "If I'm confirmed I will research that and get back to you."