A blistering letter signed by 50 Republican national security officials states that not one of them will vote for Donald Trump come November, declaring the GOP nominee "lacks the character, values, and experience to be President."

The letter describes Trump's lack of knowledge of the Constitution and U.S. laws and lambastes the candidate for appearing to have "no interest in educating himself."

Among those who signed the letter are former Deputy Attorney General Donald Ayer, former Deputy National Security Adviser for Strategic Planning Robert Blackwill and former Secretary of Homeland Security Michael Chertoff. 

"A president must be disciplined, control emotions, and act only after reflection and careful deliberation," the letter states. "In our judgment, Mr. Trump has none of these critical qualities ... We are convinced that in the Oval Office, he would be the most reckless President in American history."