WATCH: Over 100 GOP Former National Security Officials Endorse Kamala Harris

Vice President Kamala Harris has received another endorsement from another group of Republicans who believe she "possesses the essential qualities to serve as president and Donald Trump does not."

Over 100 Republican former National Security leaders have written an open letter stating why they're backing the Democratic nominee rather than their own on a Substack called "Reagan, Bush, McCain & Romney Alumni for Harris."

The group includes former Congressman and January 6th House Select Committee member Adam Kinzinger, Chuck Hagel, a former senator who served as defense secretary under Donald Trump, and John Negroponte, a director of national intelligence for George W. Bush.

"We are former national security and foreign policy officials who served in the administrations of Presidents Ronald Reagan, George H.W. Bush, George W. Bush, and/or Donald Trump, or as Republican Members of Congress," the letter opens. "We have served in the White House, the Departments of Defense, Treasury, State, Justice, Homeland Security, Commerce, and other agencies and in Congress. 

"We believe that the President of the United States must be a principled, serious, and steady leader who can advance and defend American security and values, strengthen our alliances, and protect our democracy," the letter continues. "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."

Brig. Gen. Steve Anderson joined Nicolle Wallace on "Deadline: White House" to discuss Republicans overwhelmingly choosing Vice President Harris over Trump.