Elizabeth Warren, the progressive favorite who’s vying for Republican Scott Brown’s Senate seat in Massachusetts, has a new target: JPMorgan Chase CEO Jamie Dimon.

Dimon has been criticized for the $3 billion hit JPMorgan’s took on a bungled hedge by a London trader. In a release blasted out to reporters on Tuesday, Warren said Dimon should step down from the board of the New York Federal Reserve Bank in the wake of his firm’s big loss. Warren’s call for Dimon’s resignation comes on the eve of the CEO’s appearance before the Senate banking committee to testify about the bad trade.

Here’s more from Warren:

“Jamie Dimon should take the opportunity of this hearing to step down from the New York Fed’s Board, and Congress should pass legislation that will prohibit these kinds of conflicts of interest in the future,” said Warren.

“Four years after the financial crisis, Wall Street has still not been held accountable, and that lack of accountability has history repeating itself—huge, risky financial bets leading to billions in losses. It is time for some accountability,” said Warren. “It’s really frustrating to see these Wall Street firms make the same mistakes over and over again, and for the CEO’s who run these companies to escape accountability. Dimon stepping down from the NY Fed would be at least one small sign that Wall Street will be held accountable for their failures.”