“Joe Biden is running for reelection, and I will be his ticket mate,” Harris told CNN earlier this week. “Full stop.” (She later revised her remarks to say that Biden “intends” to run.)

Even if we do that, there’s another question that’s at least worth asking: Would Biden face a primary challenge?

Right? Right!

Now, before I go any further, it’s important to draw a distinction here between a serious and credible primary challenge to Biden and just someone deciding to run to propel an issue (or themselves) into the national media limelight.

The latter is relatively likely to happen — a sort-of shoestring candidacy that never really threatens Biden or even draws his attention in a meaningful way.

The former is rarer — despite Pritzker’s comment.

The only time a Democratic president was seriously challenged for his party’s nomination in his reelection bid was in 1980, when Jimmy Carter, the incumbent, had to deal with a challenge from Massachusetts Sen. Ted Kennedy.

Carter won that primary, narrowly, but the damage inflicted by it played no small part in his blowout loss in the general election to Ronald Reagan.

Yes, there are comparisons between Carter and Biden — at least at this stage of his presidency. Both men used economic stimuli to lower the unemployment rate and help restart a flagging economy. And both have had to deal with the resultant inflation. Neither man was (or, in Biden’s case, is) terribly popular with the general electorate. And their liberal party bases didn’t (and don’t) see eye to eye with them.

But there’s a reason that it’s been more than 40 years since a Democratic president (or, really, any president) has faced a serious primary challenge: Incumbency is a powerful thing — especially in this age of billion-dollar campaigns and nonstop politicking.

It’s very, very hard to beat an incumbent — even a damaged one like Carter or Biden.

With all of that said, Pritzker represents a unique challenge for Biden if he did decide to run. His family owns the Hyatt hotel chain and his estimated net worth is well north of $3 billion. Which means that if Pritzker wants to run against Biden in 2024, he won’t lose for a lack of funds.

The Point: History suggests a serious primary challenge to Biden is unlikely. But not impossible.