President Donald Trump's critics are increasingly focused on the question of which Democrat will challenge him for the presidency in 2020. It's an important question, but another one might be even more important: Regardless of who runs in 2020, if Trump loses, will he leave the Oval Office peacefully? Let's start with why we need to ask this question: Trump is increasingly proving himself to be a President eager to overstep his authority. Just last week, Trump displayed his willingness to invoke unprecedented presidential power to declare a national emergency utterly without justification. This week has brought a startling report...