In interviews with voters and activists at stops in conservative western Iowa and then at the presidential forum in Des Moines, it was clear they do not see Carson as equally up to the challenge. In fact, the characteristics once cited by voters here as boosting Carson – his soft-spoken nature and disinterest in attacking his competition, for example — are now seen as problematic.

“Carson, he’s a wonderful guy, but we like Cruz better,” said Judy Kirby of Des Moines, who said she is gravely concerned about foreign policy in the wake of several high-profile terrorist attacks. Cruz “seems more knowledgeable, he seems stronger.”

Voters described Carson as “lacking fire in the belly,” as being a nice person but too “soft-spoken,” and said he doesn’t come across as sufficiently tough. That’s in contrast to both Donald Trump, a tough talker who pledges to “bomb the sh** out of” ISIL, and Cruz and Rubio, who have both sought to demonstrate Senate-acquired policy chops.

“It’s probably one of [Carson’s] weakest stances,” said Chris Boley, a business owner who attended the Family Leader event and is now leaning toward Rubio. “That doesn’t mean he can’t get up to speed, but he has some catching up to do…In this day and age, with how important national defense is, with terrorism in the Middle East, you’ve got to be real studied.”