“I’m still between Hillary and Bernie,” Mr. McCombs said.

“She’s the one we like the best, who we think will carry on with our civil rights,” Ms. Pollard told him, mentioning her wife, Gayla Snook. Ms. Pollard and Ms. Snook were one of Newton’s first openly lesbian couples. They began canvassing more than 15 years ago for state candidates who backed same-sex marriage. Ms. Pollard won over people vehemently opposed to gay marriage. “I put a face on it because I was at their door,” she recalled.

“Can I answer any questions about Hillary?” she asked Mr. McCombs.

“No, I’ve been reading and listening to everything,” he said.

Ms. Pollard told Mr. McCombs that when Gov. Peter Shumlin of Vermont visited Iowa as a Clinton surrogate, he had said, “That speech Sanders gives is 30 years old.”

“I like Hillary, don’t get me wrong,” Mr. McCombs said.

Ms. Pollard was in no hurry to end conversations with uncommitted voters. She lingered in people’s foyers, or even outside in a bitter wind, to the point of awkwardness. Noticing a photograph on the wall of Mr. McCombs posing on a beach, she said, “That’s a great picture of you.”

“It’s a fake,” he said. “We were on a cruise.” The backdrop was painted.

“O.K., anything else?” Mr. McCombs asked, standing in sweatpants and socks as the television played.

“O.K., Joe, have a good one,” Ms. Pollard said as she backed out.

At another home, Eileen Johnson, a grandmother, said, “Hillary, she gives you hope that things can be better.” But after 20 minutes of conversation while Ms. Johnson’s cat pawed at Ms. Pollard’s legs, Ms. Johnson was no closer to a decision. “It’s just a matter of what the good Lord wants for us, I guess,” she said.