The contrast between the rallies of the two candidates is jarring:
Voters have mobbed Mr. Sanders at events since Friday, some jumping over chairs to shake his hand, snap a selfie or thank him for speaking about the middle class. “Did you get to touch him?” asked one woman who could not get close enough after an event here on Saturday.
“We love you, Bernie! Enough is enough!” Nathan Arentsen, 29, cheered several times at another event in Des Moines as he stomped his feet to signal support for the candidate.
Audiences for Mrs. Clinton have yet to grow to consistently match those for Mr. Sanders, and the typical reception for her was evident on Monday in Waterloo. About 300 people welcomed Mrs. Clinton enthusiastically and listened to her diligently, but many of them, still unsure, rebuffed Clinton aides trying to get them to sign “commitment cards” to caucus for her.