In light of my previous two posts, I have been scanning American history to determine whether there are precedents for a candidate running purely as the mouthpiece of the incumbent. Madison (Jefferson), Monroe (Madison), Van Buren (Jackson), and George H.W. Bush (Reagan) don’t really fit the bill, because they were politicians of considerable reputation in their own right. Vance, as a national figure, had about as much heft as Dan Quayle before Trump chose him as his running mate.
The closest precedent would be Taft, who ran and won as TR’s anointed candidate. You will recall that the Taft episode didn’t end well for the GOP. TR ultimately turned on him and ran as a third-party candidate, thus handing the presidency to Wilson in 1912.