The Florida senator, who Trump ruthlessly mocked as “little” and “sweaty” throughout the primary race, so despised his antagonist that he made the ill-fated decision to hit back in kind, mocking Trump’s makeup and hand size. After he dropped out, it took several months for him to embrace Trump, though he could not bring himself to appear at the R.N.C. in person to make the endorsement, sending in a video instead.