EAST AMANA, Iowa — Anna Navin stepped out of her Honda, grabbed a large pink backpack from the passenger seat of her car and knocked on the door of Glenn Goetz, a 68-year-old retiree.

Navin, a 28-year-old organizer for Sen. Elizabeth Warren (D-Mass.) was meeting with Goetz to see if he would take on more duties as a precinct captain, including knocking on doors in other nearby communities and helping recruit volunteers.

As she stepped inside, Navin and Goetz greeted each other like old friends, and after a few months of running into each other at county parades and at volunteer events she had hosted on Warren’s behalf, they were. He offered her a cup of tea and a plate of freshly baked cookies as they sat down at his kitchen table to strategize about an area he was planning to canvass.

He had already been to the neighborhood, and he wondered if it was too aggressive. “You know, the more we talk to these caucus-goers, the better,” Navin assured him. “People will know you as the Warren guy.”