Sen. Elizabeth Warren, along with other senators, are calling for the Fed to crack down on large regional banks. Warren is pictured here during a senate hearing on March 7. Credit: Tom Williams / CQ-Roll Call, Inc./Getty Images

(CNN) — Senator Elizabeth Warren is cranking up the pressure on the Federal Reserve following the collapse of Silicon Valley Bank.

In a new letter shared exclusively with CNN, Warren, Sen. Bernie Sanders and ten other senators are calling for the Fed to crack down on large regional banks with assets between $100 billion and $250 billion.

Both Silicon Valley Bank and Signature Bank fit into that asset threshold when they failed earlier this month. The bipartisan 2018 rollback of Dodd-Frank freed large regional banks in that range of assets from the toughest oversight.

“The fall of both SVB and Signature, the near-crash of First Republic, and the struggles of other regional banks shed new light on the systemic important of banks with assets totaling between $100 billion and $250 billion,” the lawmakers wrote in a letter sent Wednesday to Michael Barr, the vice chair for supervision at the Fed.

The dozen lawmakers note that the same 2018 rollback of Dodd-Frank gives the Fed latitude in applying tougher regulation on banks in this category — including stronger capital, liquidity, stress testing and resolution plans.

Notably, the letter was signed by Senator Angus King, the Maine independent who voted in favor of the 2018 rollback. It was also signed by Sanders and Democratic Senators Jack Reed, Tammy Duckworth, Richard Blumenthal, Mazie Hirono, Ed Markey, Sheldon Whitehouse, Tina Smith, Chris Van Hollen and Brian Schatz.

“Irresponsible and excessive risk taking by SVB and Signature executives should serve as a clear reminder that banks cannot be left to supervise themselves,” Warren and the other Senate Democrats wrote. “The Fed has a responsibility to ensure financial stability, and in order to fulfill that responsibility, it must ensure that all banks with potential systemic significance are subject to rigorous safety and soundness rules.”

The lawmakers argue that the federal intervention in the wake of the SVB and Signature failures underscore the systemic risk posed by troubles in banks of this size.

Treasury Secretary Janet Yellen said Tuesday that US officials took “decisive and forceful actions” to calm the banking crisis after the bank failures.

What will the Fed do?

Days after the bank failures, the Federal Reserve launched a review of the regulation and oversight of Silicon Valley Bank. That review is being led by Barr, who President Joe Biden nominated to be the Fed’s top regulator of Wall Street.

Fed Chairman Jerome Powell, a frequent target of Warren’s criticism, called for a “thorough, transparent and swift review” by the Fed.

The Fed is rethinking some of its own rules related to midsize banks, including potentially ramping up capital and liquidity requirements and stepping up annual “stress tests,” the Wall Street Journal previously reported.

“We strongly support this approach,” Warren and her colleagues wrote in the letter. “In order to restore sufficient safety practices to the banking system and restore consumers’ confidence in the soundness of their banks, the Fed must immediately exercise its authority to apply enhanced prudential standards and supervision to banks with $100-$250 billion in assets.”

Warren has long been a regulation hawk, pushing for tough rules to prevent a repeat of the 2008 crisis and sharply criticizing those who have relaxed rules on banks.

‘Serious mistake’

However, the role of the 2018 rollback of Dodd-Frank in the failure of Silicon Valley Bank is hotly debated

Mark Zandi, chief economist at Moody’s Analytics, recently told CNN’s Kate Bolduan he doesn’t know if the easing of stress test requirements “would have forestalled” the bank failures, adding these stress tests “couldn’t have hurt.”

Sheila Bair, a Republican and the former chair of the FDIC during the 2008 crisis, told CNN’s Poppy Harlow she doesn’t think there is “some broad problem because of deregulation with regional banks.”

Patricia McCoy, a former federal regulator, told CNN on Tuesday that the events of the past ten days have shown the 2018 rollback of Dodd-Frank for banks in the $100 billion to $250 billion asset range was a “serious mistake.”

“Fast forward five years, and two of those banks — Silicon Valley and Signature Bank — failed due to lack of liquidity and possible undercapitalization,” McCoy, now a professor at Boston College Law School, said in an email. “Their failures destabilized the financial system in the process and caused federal banking regulators to take measures (such as insuring all the deposits at the two failed banks) that will tempt banks to bet on even bigger risks in the future.”