Accused White House Correspondents’ Dinner gunman Cole Allen sent a sprawling manifestoto family members about 10 minutes before Saturday’s attack, sources told The Post.

The 1,052-word missive obtained by The Post Sunday morning — signed “Cole ‘coldForce’ ‘Friendly Federal Assassin’ Allen” — outlined his “rules of engagement” for the shooting and stated he believed it was his righteous duty totarget administration officials.