The odds of Joe Biden running for reelection are now very high, but since we keep hearing of polls where Democratic voters are restive, it’s worth pondering the road that probably won’t be taken, so I did that at New York:

The estimable New York Times columnist Michelle Goldberg recent came out and said what a good number of Democrats occasionally think: They like Joe Biden and think he’s done a good job as president, but they’d rather see the 80-year-old step aside and let someone else run in 2024. Goldberg was very direct about it:

“It’s been widely reported that Biden plans to use the State of the Union to set up his case for re-election. There’s a rift in the Democratic Party about whether this is wise for an 80-year-old to do. Democratic officials are largely on board, at least publicly, but the majority of Democratic voters are not. ‘Democrats say he’s done a good job but he’s too old,’ said Sarah Longwell, an anti-Trump Republican strategist who conducts regular voter focus groups. ‘He’ll be closer to 90 than 80 by the end of his second term.’ Perhaps reflecting this dynamic, a Washington Post/ABC News poll showed that while 78 percent of Democrats and Democratic-leaning independents approved of the job Biden has done as president, 58 percent of them wanted a different candidate next year.”

Regardless of what Democrats may want, the odds of Biden stepping aside are very low. The last sitting president to retire on his own terms after just one full term was Calvin Coolidge nearly a century ago. There are zero signs of any serious challengers stepping up to challenge Biden’s renomination, and restive Democratic voters will almost certainly come around once the 46th president becomes the party’s standard-bearer again.

But it’s worth considering what might happen if Biden does step aside. Goldberg’s view of this scenario is fairly sunny:

“Plenty of Democrats worry that if Biden steps aside, the nomination will go to Vice President Kamala Harris, who polls poorly. But Democrats have a deep bench, including politicians who’ve won in important purple states, like Gov. Gretchen Whitmer of Michigan and Senator Raphael Warnock of Georgia. Biden said he wanted to be a bridge to the next generation of Democrats. There are quite a few promising people qualified to cross it. A primary will give Democrats the chance to find the one who is suited for this moment.”

Unfortunately, a contested 2024 Democratic primary probably wouldn’t be a calm, deliberative process. It would more likely be a nasty and complicated slugfest leading to a shaky general-election campaign. The GOP presidential field is coming together pretty late compared with previous cycles, and even if Biden made a call soon, Democratic candidates would find themselves scrambling to put together a national campaign. Here are some likely consequences of a sudden Biden retirement.

Kamala Harris would run, but she wouldn’t clear the field.

The vice-president is Biden’s heir apparent, though most observers figured she would have until 2028 to polish her image and (assuming she and Biden were reelected) chalk up some distinctive accomplishments. Harris’s candidacy could get a big boost if Biden promoted her candidacy, but he might decide it’s more appropriate to stay out of the nominating process, much as Barack Obama did in the early stages of the 2016 primaries. Even with Biden’s active support, though, it’s unlikely Harris has the sort of political clout to preempt a challenge.

Furthermore, Harris might have to prove her appeal to Black voters. In 2020, Black voters strongly preferred Biden to Harris, ruining her efforts to pursue a strategy modeled on Obama’s in 2008. Would she do better with this crucial segment of the primary electorate in a second presidential campaign? It’s unclear, particularly if the “electability” concerns that helped boost Biden among Black and white voters alike turn out to be a millstone for Harris.

2020 candidates would flood the race.

In 2020, the Democratic primary field was the largest since the start of the modern primary system, and the many candidates who performed better than Harris would certainly be tempted to challenge her again.

Two progressive heavyweights, 81-year-old Bernie Sanders and 73-year-old Elizabeth Warren, probably retired their own presidential ambitions on the assumption that Biden would be the party’s candidate in 2024. But if he’s not in, they might consider running. In particular, the huge following Sanders built over two presidential campaigns might convince him to run again; he has pointedly not ruled out a bid if Biden isn’t in the field.

There are also younger 2020 candidates who envision themselves in the White House and may accelerate their plans given the surprising appearance of an “open” nomination contest and the uncertainty as to when the next “opening” might occur. For some reason, Pete Buttigieg is often the sole object of speculation on this possibility, but Amy Klobuchar, Cory Booker, Julian Castro, and even Michael Bennet might go for the gold again.

The primary would attract plenty of fresh candidates, too.

The 2024 primary field could be even more crowded than it was four years earlier. There are several major Democratic officeholders thought to be waiting for the right moment to run for president. If Biden doesn’t run, that moment might arrive early for three governors: California’s Gavin Newsom, Illinois’s J.B. Pritzker, and Michigan’s Gretchen Whitmer. The first two governors have vast resources at their disposal, while the third checks an awful lot of boxes for Democrats valuing electability above all else.

The fight over the Democratic primary calendar would become red hot.

Right now, the Democratic National Committee’s Biden-driven bid to shake up the presidential primary calendar is a bit of an abstract proposition; it doesn’t really matter if Biden runs unopposed. If Biden isn’t the nominee, it will suddenly matter a great deal whether the primaries begin with South Carolina rather than New Hampshire, whether Iowa is excluded from the early states altogether, and whether Georgia or Michigan go third or fourth or fifth. In a late-developing open nomination contest, candidates may rise or fall based on how well they navigate the new calendar. So the DNC’s tentative decision to move ahead with a new order of states could suddenly become controversial and even disputed.

Democrats would fall right back into “disarray.”

Democrats are rightly proud of the unity they have been displaying in Congress lately in sharp contrast to the chaos and factionalism of the GOP.

But the relative ideological unity of the Democratic Party would by no means guarantee a peaceful nomination process if Biden retires. In primaries in which everyone is mostly aligned on the issues, candidates tend to differentiate themselves on personal matters, often leading to especially nasty battles. Warren’s demolition of billionaire Michael Bloomberg’s 2020 candidacy candidacy in just one debate could provide the template for 2024. And, ideology aside, a competitive contest could revive disagreements over race and gender at a time when the Democratic coalition couldn’t afford any self-inflicted wounds.

Costs could be high for Democrats.

A Biden retirement might air out some dirty Democratic laundry and help identify future talent, but it would come at a high price. The money and energy that would be siphoned off into what would almost certainly be a big fight involving a large field of candidates could be more usefully deployed on behalf of a Biden-Harris reelection campaign. Yes, there’s a risk in moving forward with an 80-year-old nominee who doesn’t excite Democratic voters. But it’s not as big a risk as distracting Democratic voters with the carnage of a primary fight while Donald Trump or Ron DeSantis waits to pick up the pieces and blast all Democrats to perdition.