In modern US history, a sitting president has abruptly declined to seek renomination in an election year on only two occasions. Harry Truman dropped out in March of 1952 after being upset in the New Hampshire primary. Around the same stage in the 1968 race, Lyndon B. Johnson announced that he would not seek renomination, amid widespread opposition to his handling of the Vietnam War. In both instances, the Democratic Party ultimately lost the general election.
But one cannot draw any general conclusions about the wisdom of switching standard-bearers in an election year from these facts. This is because you cannot responsibly glean any general rule from a correlation supported by two data points. It is true that Donald Trump won a general election when Democrats nominated a candidate under 70 years old in 2016, but then lost when Democrats nominated a candidate over 70 in 2020. But it would be bizarre to look at those facts and conclude that “In the whole picture of American history, when Democrats nominate a non-septuagenarian to take on Donald Trump, the candidate loses.”
Richardson’s reasoning is only a bit less absurd. In 1952, the Democratic Party had held the White House for 20 consecutive years, and the GOP picked a moderate, popular general, Dwight Eisenhower, as its nominee. Is it not possible that Democrats lost for these reasons, rather than because Truman stepped down? For all we know, the party could have done even worse if Truman had been the nominee; we do not have access to the counterfactual. We can’t get in a time machine, change one variable, and then run history again. And without the benefit of such an experiment, we cannot know with certainty whether Truman dropping out helped or hurt his party.
The same can be said of LBJ’s decision to withdraw from the 1968 presidential race. Maybe the Democrats lost that election for the reasons Richardson states: Johnson dropped out, and his replacement, Hubert Humphrey, struggled to win as much support because the “party apparatus” was built around LBJ (whatever that means) and the news media reported on opposition research about Humphrey.
But how precisely are we proving that thesis? How do we establish that Democrats would have done better with Johnson on the ballot? After all, LBJ was even more closely identified with the Vietnam War, and therefore even more likely to internally divide the Democratic coalition, than Humphrey was. And many features of that election cycle favored the Republicans, including a widespread backlash to civil rights and rising crime. Despite these headwinds, Humphrey nearly won the popular vote. How do we know that LBJ wouldn’t have done worse?