In Iowa, party leaders grimly contemplated the end of a four-decade run in the national spotlight with a borderline gallows humor.

“It almost gets to the point of three strikes you’re out,” said Bret Nilles, the Democratic chairman of Linn County, whose population is second biggest in the state, referring to a bipartisan history of earlier caucus blunders in 2016 and 2012…

Leah D. Daughtry, a member of the Democratic National Committee, which sets the rules for the party’s nominating contests, said the chaos would move more fellow committee members “to get on the bandwagon” to change the system.

“As my Momma said, there’s a good reason and the real reason,” Ms. Daughtry said. “The good reason is it was a debacle last night, but the real reason is Iowa is just not representative of what the country has become and of the Democrats as a big-tent party.”