Sen. John Fetterman (D-PA) blasted Graham Platner, the Democratic Senate nominee in Maine, as the “king of the dirtbags,” highlighting growing tensions within the party after another socialist won a congressional primary in Colorado.

After a sweeping win from Melot Kiros, a 29-year-old socialist, in Colorado’s 1st Congressional District over Rep. Diana DeGette (D-CO) and a string of socialist primary victories in New York City, critics warn that socialists are surging in popularity.