For some reason our political culture has gotten away from the idea of a President running for reelection replacing their Vice President on the ticket. It didn’t used to be so. Lincoln and FDR both replaced their running mates (FDR did it twice.) I think that part of it might be the primary system. Since 1980 every major party nominee has gone into the convention with a majority of the delegates. The nominee controls (more or less) the convention. Carter lost some platform votes to Carter in 1980 when some Carter-pledged delegates defected on some issue votes, but it wasn’t like the Kennedy forces could force Mondale off the ticket even if they wanted to. For most practical purposes, the presidential nominee is chosen by voters in primaries and caucuses and then the presidential nominee chooses the running mate. We no longer have the bargaining between politicians at the convention about either the top or the bottom of the ticket. This makes the running mate much more unambiguously the choice of the presidential nominee than was the case earlier. That means the President can’t hide behind the will of the convention on either the matter of the original choice or the replacement. It also means that if a President running for reelection dumps his running mate for what looks like “political” reasons, then the President would seem to be admitting a major error in judgment. On the whole, I think this particular aversion to replacing running mates is unfortunate.
