Senate Republicans could convict, or threaten to convict, thereby pressuring Trump to resign. They could even work out a deal by which they acquit in exchange for Trump not seeking a second term. Each of these options would leave the Republicans in need of a compromise candidate with very little time left on the clock. Republicans would need someone who understood the requirements of a national campaign, someone with widespread (and largely positive) name recognition, and someone on the record opposing both Trump and Trumpism. Senator Mitt Romney is all of those things. Running Romney would immediately alienate the Trump...