More than 100 Republican former national security and foreign policy officials on Wednesday endorsed Kamala Harris for president in a joint letter, calling Donald Trump “unfit to serve” another term in the White House.

Former officials from the presidential administrations of Republicans Ronald Reagan, George H W Bush, George W Bush and Donald Trump, as well as Democrats Bill Clinton and Barack Obama voiced their support for Harris, the Democratic nominee for president in this November’s election. They were joined by some former GOP members of Congress.

The letter said: “We believe that the president of the United States must be a principled, serious, and steady leader.”

It went on: “We expect to disagree with Kamala Harris on many domestic and foreign policy issues, but we believe that she possesses the essential qualities to serve as president and Donald Trump does not. We therefore support her election to be president.”