56 foreign policy experts who have publicly supported President Joe Biden sent him a letter on Friday saying he should step down as the Democratic Party s presidential candidate for the good of the country.

With the deepest appreciation for your many decades of inspired leadership, we strongly believe that ongoing concerns surrounding your continued candidacy and the growing likelihood of an electoral college victory for Donald Trump put your national security accomplishments and our country and your legacy at an unacceptable level of risk, reads the message.

HuffPost first revealed the text of the letter on Thursday evening.

Donald Trumps vision, approach, and expressed intentions concerning our nations security are in fundamental conflict with the values and principles for which you have stood ... We strongly believe that now is the time to pass the mantle of leadership and we respectfully urge you to do so, the message continues.

The message cites Bidens accomplishments abroad in Europe, Asia and the Americas and on international challenges like climate change.

The signatories include several former high-ranking foreign policy officials, like former national security adviser Tony Lake, and several officials who have worked under Biden, like former Pentagon official Rosa Brooks and Afghanistan expert Barnett Rubin.

The lead organizers of the letter are Eric Schwartz and John Shattuck, two former senior officials at the State Department, according to the distributed copy viewed by HuffPost. Shattuck was also an ambassador, and Schwartz served at the White House National Security Council.

The petition was circulated Thursday morning and by that evening had attracted several dozen signatures, including those of prominent former national security officials, a source familiar with the letter told HuffPost.

The development comes amid an uptick in skepticism of Bidens candidacy among elected Democratic officials, and amid polls suggesting he is trailing his Republican rival, former President Donald Trump.

Additionally, a group of former aides on Thursday released an open letter asking Biden to exit the race, as USA Today reported . The Bulwark first revealed the existence of the petition from former national security staffers.

The president often treats his experience working on global affairs as a former chairman of the Senate foreign relations committee, then as vice president, and finally as commander in chief as a major selling point.

According to Puck News, Biden argued in a Saturday call with Democratic lawmakers: Name me a foreign leader who thinks Im not the most effective leader in the world on foreign policy.