Mark Sanford isn't the only one.
Trump has 3 challengers.
William Weld
Joe Walsh
Mark Sanford
I can't recall a sitting president having 3 from his own party challenging him.
I do know that presidents who have challengers usually lose the general election.
Some republicans aren't happy about it and have canceled their state's primary to guarantee those challengers aren't too much of a threat to trump.
This from the same party that screamed cheating when Hillary was running.
The DNC didn't cancel any primaries when she was running. In fact I can't think of an election that had a challenger to the president where a state canceled their primary. Sure it's done when there's no challenger but not when there are 3.
What is trump so afraid of?
Republicans to scrap primaries and caucuses as Trump challengers cry foul