About 100 feet of sawhorse barrier lined the entrance to Hillside Middle School here in Manchester, N.H., unintentionally evincing the divide in the New Hampshire Democratic primary.
At one end, closest to the parking lot, stood Representative Dean Phillips of Minnesota, the lone Democratic candidate challenging President Biden. He was surrounded by about a half-dozen staff members and volunteers energetically waving signs.
At the other end were two members of the local Manchester Democrats, proudly holding signs encouraging voters to write in Joe Biden, who is not on the ballot after a clash over his effort to strip New Hampshire of its first-in-the-nation primary status.
Julie Swant, 84, who was balancing a “Write-In Biden” sign on the back of the sawhorse fence, shifted her sunny disposition while greeting voters to glare at the mere mention of Mr. Phillips’s name.
“We love Joe Biden. We were just chatting about how much he’s done, and it’s so much,” she said. Her fellow “Write-In Biden” sign holder and neighbor, Jim Webber, 68, nodded in agreement.
Back on the other end of the fence, Mr. Phillips continued to greet voters for about an hour, having arrived right as polls opened at 7 a.m. Eastern time, taking only a brief break for a radio interview from the quiet (and warmth) of his S.U.V. He approached voters as if he were a stranger to them, even as he was flanked by multiple signs bearing his name.
“Good morning!” Mr. Phillips shouted to voters as they strode into the polls around 7:30 in the morning, his hand outstretched for a handshake. “Do you know who I am?”
Supporters, however, were brought in for extended handshakes, with Mr. Phillips holding their grasp for 15 seconds or longer. Poll workers briefly came outside eager to take a picture with a candidate, bringing their own disposable camera for a photo.
Some voters, like Richard Valley, 53, who works in retail management and lives in Manchester, earned a hug.
“Joe Biden just needs to go. It’s time to retire,” Mr. Valley said (though he added that he would vote for Mr. Biden over Mr. Trump).
In an interview, Mr. Phillips called the day “the most joyful, wonderful day I think in my life to be part of this.”
He batted away any concerns that his presence in the race, and his criticisms of Mr. Biden’s age, were dividing the Democratic Party ahead of a critical election. “What I’m worried about is the fact that we are coronating a candidate who simply can’t win.”
And he sought to clarify his flirtation with a No Labels run. “I’ve made it really clear: I’m a Democrat. I’m a lifelong Democrat who flipped a Republican seat that had been red for 60 years.”
But, he added, “if it’s Biden versus Trump, we need some alternative way to draw votes from Trump and win this election.”
“I’m trying to keep people’s minds open to a No Labels candidate who would draw votes from Trump. That wouldn’t be me. That’s the whole point,” Mr. Phillips said.