[....] Joe Biden’s approval ratings remain low. A majority of Democrats don’t want him to run for another term.

This would seemingly open the door to a primary challenge.[....]

For Biden to start dropping, Democrats would have to stop thinking he’s doing a good job as president. Biden’s approval rating among Democrats in a Quinnipiac University poll released last week was 84%. Just 16% either disapproved (13%) or didn’t hold a view (3%).There is no precedent – at least since World War II – of an incumbent president losing a contested state primary while polling above 70% nationally within his party.

Over the past 50 years, the two biggest primary challenges to incumbents occurred in 1976, when Gerald Ford’s approval rating among Republicans was in the 60s, and in 1980, when Jimmy Carter’s approval rating among Democrats was in the 60s.

Biden also scores high on a slightly different intraparty metric: His favorability rating is at 85% on average. That is, most Democrats think he’s doing a good job as president and are fans of him personally.[....]