One-man Cabinet: Marco Rubio went from rival to Trump's point man, but can he handle it?

In a surprising twist of fate, Marco Rubio has gone from bitter presidential rival to President Donald Trump’s go-to guy. 

At the start of the new administration, current and former officials speculated Rubio would be one of the first Cabinet officials shown the door, as his America First credentials were called into question given his previously hawkish foreign policy views. 

Instead, Rubio has only continued to find favor with the president – so much so that he now holds an unprecedented...