Mnuchin, making his first appearance before the Senate Banking Committee since taking over as treasury secretary, said in a heated exchange with Sen. Mnuchin said he reviewed cases at the Committee on Foreign Investment in the United States (CFIUS) every week.
Towards the end of a typically contentious interaction with Warren, Mnuchin said it would be a "huge mistake" to break up big banks.
But Mnuchin insisted Thursday that his call for a modernized version of that law does not include a strict firewall that would break up some of the biggest names on Wall Street.
Advocates of reintroducing Glass-Steagall for federally insured commercial banks say it would discourage risky behavior by banks. We, during the campaign - and I had the opportunity to work with the president on this - specifically came out and said we do support a 21st Century Glass-Steagall. This week, Tim Pawlenty, the head of the industry lobby the Financial Services Roundtable, told Bloomberg that, when the administration says "21 century Glass-Steagall", what they really mean is deregulation.
Mnuchin was given a chance to elaborate on the administration position by Sen. All three have substantial footprints in commercial and investment banking, so their business models would be buffetted.
With no concrete plan on how the White House proposes to follow through on such major tax cuts, the secretary said that Treasury is preparing tax principles to provide a "roadmap for that administration's approach to financial regulation".
"This is freaky!" fumed Warren, a Massachusetts Democrat, at Mnuchin during a hearing on Capitol Hill that quickly turned contentious when it was her turn to question the Treasury chief.
And Trump has made statements that seem to suggest he supports the idea.
Warren tried repeatedly to get Mnuchin to explain what "21century Glass-Steagall" is supposed to mean without separation of bank functions.
The Glass-Steagall Act was signed into law in 1933 by President Franklin D. Roosevelt. "This is like something out of George Orwell", Warren said, alluding to the concept of doublespeak from Orwell's dystopian novel, "1984".
WARREN: Just tell me what 21st Century Glass-Steagall means if it doesn't mean breaking apart those two functions. Brown demanded. "People want to know about those entanglements". "We do think there are potential things we could look at around regulation, but we do not support separation of banks and investment banks".