Pete Buttigieg might just be the new 2020 Democratic front-runner. At the very least, he has officially entered the top tier: Polling shows the South Bend, Indiana, mayor topping the polls in the early-voting state of Iowa, and some new polls show him surging in New Hampshire as well.

This rise means it’s Buttigieg’s turn for a debate stage pile-on. Here’s what Democratic candidates ought to scrutinize the mayor on during tonight’s MSNBC Democratic debate in Atlanta, in order to illuminate his shortcomings for primary voters.