That’s not always true, there has been one example where the incumbent lost their primary, Franklin Pierce.
He was the 14th president, winning the 1852 election. His handling of the political climate before the civil war didn’t get him enough support for the 1856 election, ultimately losing the primary bid to James Buchanan.
That’s not even considering the multiple times when someone took over for deceased presidents, then lost their own reelection primaries afterwards.
So there is precedent for not using the incumbent. It’s just usually logical to pick the person that’s already won before.
That’s not always true, there has been one example where the incumbent lost their primary, Franklin Pierce.
He was the 14th president, winning the 1852 election. His handling of the political climate before the civil war didn’t get him enough support for the 1856 election, ultimately losing the primary bid to James Buchanan.
That’s not even considering the multiple times when someone took over for deceased presidents, then lost their own reelection primaries afterwards.
So there is precedent for not using the incumbent. It’s just usually logical to pick the person that’s already won before.
Fair. Still, it is a rare exception to the rule.