It can be difficult work, but even in an era of digital advertising and blast texts, canvassing is considered the gold standard in political organizing. Face-to-face contact is proven to increase the odds that a voter will actually turn out. “The way you get there isn’t spending another $2 million on television ads,” said Ms. Jones. “It’s spending time to build an army on the ground.”
In Nevada, and especially in Clark County, which includes Las Vegas, unions have become powerful engines for turning out voters. Ms. Henry said S.E.I.U. members in the state had already knocked on the doors of 15,000 Hispanic and Asian voters, and the union brought a couple of hundred of its California members to Nevada by bus to participate in mobilization activities on Saturday, the first day of early voting in the state.
There may be no stronger grass-roots political force in Clark County, which is home to more than three-quarters of the state’s population, than Culinary Workers Union Local 226, known in the county simply as Culinary. The 57,000-member union grants scores of service workers monthslong leaves of absence from their jobs as cooks and cleaners to focus on political outreach. The union has thrown its weight behind Ms. Rosen.
Such a playbook, however, is difficult to replicate in other states.
In California’s Central Valley districts, which are heavily agrarian, Latinos “have not had a lot of communication, particularly at their doors, by Democrats — either because these districts have not been in play for quite some time, or the Democratic campaign efforts were just woefully underfunded,” said Katie Merrill, the chief strategist for Fight Back California, a Democratic group.
Hispanic voters could decide the half-dozen competitive House races in California, but their participation rate remains a big question mark. To win in those seats, the Democrats “ need more of those Latinos to turn out, the ones who are not frequent voters,” Ms. Merrill said.
In Representative David Valadao’s Central Valley district, Mr. Valadao’s Democratic rival, T.J. Cox, has tried to make the race a referendum on Mr. Trump. Mr. Valadao won re-election by 13 percentage points even though Mr. Trump lost the district by more than 16 points.