The contradiction points to the twisted logic that is set to dominate Tuesday’s debate in South Carolina. The six other candidates onstage have about a week left to blunt Sanders’s momentum, according to multiple analyses by rival candidates. They say Sanders is on track to emerge from the Super Tuesday primaries on March 3 with an insurmountable lead in the delegate hunt.

But after giving Sanders a pass for most of the year, any attacks Democrats launch on the self-
described democratic socialist could undermine the party’s chance of beating Trump in November if Sanders becomes the nominee. They also risk a backlash from voters who have repeatedly punished candidates who go negative on other Democrats in this race.

“There is always a reticence to want to get on the bad side of someone who is going to be the potential nominee and president,” said Tim Miller, who advised former Florida governor Jeb Bush when he found himself in a similar position with Trump in the 2016 GOP primary. “With Trump looming, I think Democrats are going to be especially skittish to want to be seen as doing anything that is helping an absolutely loathed incumbent president.”