Some things I've noticed about low-charisma Presidential election winners

[darklordoftech]

In both the primaries and the general election, they didn't have any more charismatic opponents.

In the primaries:
1. They were the frontrunner the entire time.
2. They were the establishment favorite.

Examples I have in mind include Nixon in 1968 and 1972, HW Bush in 1988, and Romney in the 2012 GOP primaries.

[E-Dawg]

In both the primaries and the general election, they didn't have any more charismatic opponents.

In the primaries:
1. They were the frontrunner the entire time.
2. They were the establishment favorite.

Examples I have in mind include Nixon in 1968 and 1972, HW Bush in 1988, and Romney in the 2012 GOP primaries.

I would definitely argue that 2020 Biden was not charismatic either, and he was not the front runner the whole time in the primaries, and had far more charismatic opponents in both the primary (Sanders) and general (Trump).

[Property Representative of the Harold Holt Swimming Centre]

I'd say Reagan and Robertson were both clearly charismatic, and probably Rockefeller too. Ron Paul also by certain definitions. If counting candidates who dropped out before the primaries, then Herman Cain too.

[ClassicElectionEnthusiast]

In both the primaries and the general election, they didn't have any more charismatic opponents.

In the primaries:
1. They were the frontrunner the entire time.
2. They were the establishment favorite.

Examples I have in mind include Nixon in 1968 and 1972, HW Bush in 1988, and Romney in the 2012 GOP primaries.

I think you could include Bob Dole in 1996 as another example (establishment favorite, frontrunner from the start yet wasn't particularly charismatic {in 1988; Dole was more exciting compared to the ultimate vanilla candidate in Bush})

[Pres Mike]

In both the primaries and the general election, they didn't have any more charismatic opponents.

In the primaries:
1. They were the frontrunner the entire time.
2. They were the establishment favorite.

Examples I have in mind include Nixon in 1968 and 1972, HW Bush in 1988, and Romney in the 2012 GOP primaries.

I would definitely argue that 2020 Biden was not charismatic either, and he was not the front runner the whole time in the primaries, and had far more charismatic opponents in both the primary (Sanders) and general (Trump).

I think President Biden was pretty charismatic in the general though

[Republican Party Stalwart]

In regards to the general, you forgot to also mention a healthy climate for politicians of their respective party. In 1968, the disaffection felt by voters nationwide over the recently-revealed truth of the Vietnam War going poorly, and more importantly the overall state of the "year from hell," certainly made things difficult for the incumbent party, which luckily for Nixon was LBJ's Democratic Party (although to be fair, Humphrey wasn't a particularly charismatic candidate either). And then more recently, the charisma-deficient Biden certainly benefited from the COVID pandemic going on in his race against the charismatic DJT.

In regards to the primary, you forgot to mention that the low-charisma winners have often been moderate heroes able to unite two disparate factions of their respective parties, usually in cases when both of the warring factions were both completely hostile to each other but simultaneously both demoralized in their own right. In 1968, the Rockefeller/Romney/Eastern-Establishment wing and the Goldwaterite/Reaganite/Neoconservative/Buckleyite/New-Right wing were both demoralized and unconfident in their own respective abilities to win as a result of the genuine mess for the entire GOP that was the 1964 primary and general election, but both of those wings still hated each other and needed a unifying figure to be a candidate whom both wings could rally around come the general. You could perhaps say the same thing in regards to 2020 in that Biden was a sort of "unifier" of the various discernable different wings of the Dems (the Sanders lefties, the Warren soft-lefties, the Buttigieg cosmopolitans, the Beto campus/social media progressives, the John Hickenlooper middle-class moderates, the Tim Ryan/John Delaney working class moderates, the Amy Klobuchar boomer/union Dems, and any others whom you could break down).

In regards to the primary and the general, another thing that successful low-charisma candidates have benefited from is having a clear, consistent, and sizeable base. For HHH, it was labor unions, black voters, Texas, and all the other elements of the party which were loyal or beholden to LBJ and his administration. For both Hillary in 2016 and Biden in 2020, it was Black voters (perhaps followed by those labor unions still relevant and still loyal to the mainstream wing of the Democratic Party). One could say that Nixon in 1968 was helped by his record as a golden boy of the Old-Right/Robert Taft/Douglas MacArthur, dyed-in-the-wool, Union-Army-Blue no matter who, Stalwart, right-wing "Old Guard" faction of the GOP.

Also, strong experience, and a record of loyalty to and from the party at large. Biden was helped by being VP for 8 years (and I would say the fact that he was the VP of such a consequential Democratic POTUS as Obama was especially helpful, in combination with the fact that Biden never did anything particularly offensive to the anti-Obama wing of the Democrats), by having been a Senator for decades, and by having been one of the most nationally well-known and prominent Democrats for decades. Nixon was helped by having been VP for 8 years, and for having been a successful and nationally-renowned congressman and senator, despite his short tenure in both offices, who gained respect from across the party by being a prominent party spokesman and sponsor of legislation. In fact, I would also say that Nixon's status as the GOP's presidential nominee in 1960 and the California GOP's gubernatorial nominee in 1962 actually helped him in 1968, despite the fact that he lost both races (the closeness of both races probably being what prevented those losses from hurting him in 68) similar to how Hillary in in the 2016 primaries was helped more than she was hurt by the fact she had lost the 2008 primaries.

Also, in addition to being "elder statesmen"/"respected unifying figures" running against an incumbent from the other party during a time of crisis, it also helps to be a candidate who has been absent from public life in the years between the last election and the beginning of the current election season, such that the voting public sees you as refreshing rather than decrepit and boring. Nixon in 1968 was helped by having been outside of the public eye politically from 1962-1967, Hillary in 2016 was helped by having been outside the public eye politically from 2013-2015, Biden in 2020 was helped by having been outside the public eye politically from 2017-2019. In 1856, the Democratic Party nominated the rather uncharismatic candidate, then-minister to the United Kingdom, James Buchanan, in the hopes that, in the midst of the intense domestic civil strife that had been raging over slavery during the last four years of Franklin Pierce's term in the White House, voters would see Buchanan - who had been in Britain attending unrelated diplomatic duties over the course of it all - as a "fresh new face" who would do a better job than the embattled Pierce in holding the electoral map for the Democrats; come election day 1856, the Democrats found that their choice in candidate had paid off.