Carson’s support has jumped 10 percentage points since the last Iowa Poll in August, and Trump’s has fallen 4 points. This shift to a new pack leader is a thunderclap in the Republican presidential race.

“Donald Trump’s got a real problem,” GOP strategist Alex Castellanos told the Register. “Ben Carson is now the favorite to win Iowa.”

Asked which candidate they’d like to see drop out of the race, if anyone, more caucusgoers (25 percent) name Trump than any of his 14 rivals. And among both moderates and caucusgoers ages 44 or under, 36 percent would like him to quit, noted J. Ann Selzer, the pollster for the Iowa Poll.