DES MOINES — Carly Fiorina hit a walk-off homer, helium is leaking from Ben Carson’s balloon and Scott Walker’s candidacy is on life support, according to the Republicans in Iowa who will cast the first votes of the nominating contest in less than five months.

Oh, and Donald J. Trump is still Donald J. Trump — what did you expect?

A sampling of a dozen Iowans on Thursday who watched the second Republican debate — all of them close followers of the presidential race who are uncommitted — did not vary from the emerging national consensus about Mrs. Fiorina’s performance.

Perhaps the most surprising reaction was a feeling that Mr. Carson, who was on the heels of Mr. Trump in recent Iowa polls, did himself few favors on Wednesday by refusing to confront Mr. Trump, even on a medical issue like the purported link between vaccines and autism.

“Carson’s demeanor is beginning to make him look weak,” said Mary Whisenand, an insurance executive in Des Moines. “It isn’t that I think every presidential candidate needs to get out there and do hellfire and brimstone, but the optics are starting to work against him.”