From Defending Democracy Together:

We are former national security officials who served during the administrations of Presidents Ronald Reagan, George H.W. Bush, George W. Bush, and/or Donald Trump, or as Republican Members of Congress. We are profoundly concerned about the course of our nation under the leadership of Donald Trump. Through his actions and his rhetoric, Trump has demonstrated that he lacks the character and competence to lead this nation and has engaged in corrupt behavior that renders him unfit to serve as President.For the following reasons, we have concluded that Donald Trump has failed our country and that Vice President Joe Biden should be elected the next President of the United States.

Look at that list. This isn’t a bunch of lightweight GOP members.