WEST DES MOINES, Iowa — Travel with Senator Cory Booker and it will quickly become apparent that he has family in nearly every politically important state for a presidential candidate. His mother lives in Nevada. There’s the uncle from North Carolina, and a cousin in Florida.

In Iowa, the most important state to Mr. Booker’s campaign , it’s a little different: More than 80 family members live in the Des Moines area.

“I’ve got a very intimidating front row here,” Mr. Booker said on Tuesday at a rally in West Des Moines. About a dozen cousins sat a few feet from him, clad in campaign gear. One of them, Marv Allen, rose to ask a question, though he didn’t quite hold his cousin’s feet to the fire.

As the residents of Iowa prepare for an autumnal deluge of out-of-state presidential aspirants chomping pork tenderloin sandwiches and touring farms to claim a slice of the Hawkeye spirit, the senator from New Jersey can, through his relatives, come as close as any candidate in recent memory to an enviable distinction: local.