Donald Trump’s flirtation with announcing a 2024 White House bid before the midterm elections is sending signals of self-doubt and political vulnerability, with Republican operatives saying the former president is motivating challenges to his supremacy over the party. Trump would begin any presidential primary with overwhelming advantages in popularity, name identification, and resources. But pulling the trigger on a third White House campaign prior to Election Day this November, as Trump concedes is possible, might boomerang. Rather than box out potential 2024 opponents and clear the field, such a move by the former president could reek of fear, inviting more...