It had all the markings of a Washington house party: guests milling about, talk of politics and policy, a few custom cocktails and a crowd that would make a fire-code enforcer sweat.
Oh, and Senator Bernie Sanders.
Indeed, on what the campaign is calling one of the most important days of its upstart movement, Mr. Sanders came to this small apartment in southwest Washington, looked into a camera and spoke live to what his campaign said was more than 100,000 supporters nationwide.
"Enough is enough," Mr. Sanders, a Democratic presidential candidate from Vermont, told his followers, listing grievance after grievance, from income inequality to the Citizens United ruling to the minimum wage to Sandra Bland. Then he called on them to act.
The first step? A text message.
The national organizing day, which featured more than 3,500 events and house parties across the country, centered around a technological infrastructure that uses text-messaging sign-ups and a deep database of volunteers. Attendees at the house parties were asked to text a number to opt in and show interest.
A few months ago, Mr. Sanders never thought he would be speaking to this many people, telling First Draft that he would have thought that maybe 1,000 would turn out. But as he continues to draw large crowds, crowds that "continue to surprise me to this day," the campaign realized that now was the time to try and turn the interest into working volunteers.
So they borrowed a method from the labor movement and tried to structure the volunteer movement into a sort of campaign staff, from door knockers and phone bank callers to event organizers and even some computer programmers. "It's not an accident Larry Cohen is here," Mr. Sanders said, referring to the former president of the Communications Workers of America, whose remarks closed the broadcast.
At this particular party, Mr. Sanders drew a diverse crowd with equally diverse reasons for attending. There was Joe Kennedy, 61, who belongs to a spiritual group called the Network of Light and came clad in a Vermont tie-dye shirt and toting a wooden flute. He grabbed Mr. Sanders at the end of the party and offered to help in any way he could, as well as "get him a tie-dye."
Chara Espera, a 37-year-old living in Washington who had never before volunteered for a campaign, said she was moved by Mr. Sanders's message.
"I wish he was president when I was pregnant," she said, noting Mr. Sanders's policy on maternity leave.
The hosts, Manisha Sharma and Miguel Marcelino Herrera, were also newcomers to the political organizing game. They said that they were "religious conservatives" who follow the messages of St. Francis to help the poor and that Mr. Sanders's message resonated with them. After reading about the organizing day in a newspaper, they decided to offer to host a party, being told only a few days ago that their party would be the one Mr. Sanders attended.
The hosts prepared a few special things for their guest. First, a custom cocktail, the Bernie Paloma, which featured Vermont maple syrup. Then they presented Mr. Sanders with three gifts: a statue of the Virgen de Guadalupe, St. Francis and a poster of Gandhi. Mr. Sanders took the gifts with a big smile.
"This poster is beautiful," Mr. Sanders told Ms. Sharma. He read it aloud: "What it says is, 'First they ignore you, then they laugh at you, then they fight you, then you win.' Maybe that is what this campaign is about."