“I cannot think of any member of Congress who has done more within one year to fundamentally transform American politics,” Mr. Sanders said in Council Bluffs.
Yet what remains unclear, even after her positive reception this weekend, is whether Ms. Ocasio-Cortez and the political ideology that she and Mr. Sanders embrace resonates beyond Iowa’s more liberal pockets. Mr. Sanders is still running third in most polls, faces formidable competition from Ms. Warren for progressive voters and is likely to endure nagging doubts about his fitness right up until the first Iowans caucus on Feb. 3.
“It plays moderately well in blue areas, but far less well in areas that voted Republican in 2016,” said Steven Drahozal, the Democratic chair in Dubuque County, Iowa, which narrowly voted for Donald Trump over Hillary Clinton. “They have been painted as socialists, and that turns off many moderate and Republican voters.”
But if Iowans are used to seeing Mr. Sanders, they are less used to seeing Ms. Ocasio-Cortez, and several attendees expressed particular enthusiasm for catching their first in-person glimpse of her.
“Everyone loves Bernie and especially A.O.C.,” said George Holtz, 18, as he waited for the rally in Coralville to begin. “I’m excited to see him but I’m really mostly here for her.”
A student at the University of Iowa, Mr. Holtz said he was still trying to decide whether to caucus for Mr. Sanders or Ms. Warren. But he said that Ms. Ocasio-Cortez’s support for Mr. Sanders was swaying him, particularly because of what it signaled about her appreciation for his policies to combat climate change. “If Alexandria is supporting him, then I feel like I should too,” he said.
His friend, Isabella O’Connor, 19, was equally enthused about Ms. Ocasio-Cortez, even though she was an intern on Ms. Warren’s campaign.