Nearly 600 economists signed an open letter Tuesday warning that President Donald Trump’s attempt to fire Federal Reserve Governor Lisa Cook threatens the central bank’s independence and erodes trust in a key pillar of the U.S. financial system.

“Good economic policy requires credible monetary institutions. Credible monetary institutions, in turn, require the independence of the Federal Reserve,” they wrote in the letter addressed to Trump, members of Congress and the American public.

“We stand with Governor Cook and with the institutional safeguards that have long underpinned American economic strength,” they added.

The 593 signatories include Nobel Laureates Joseph Stiglitz, Claudia Goldin, Alvin Roth, Paul Migrom and Paul Romer, as well as multiple former Federal Reserve economists.

Christina Romer and Jared Bernstein, who led the U.S. Council of Economic Advisers under Presidents Barack Obama and Joe Biden, respectively, also signed the letter.