Few in Boston were thinking about the mayor’s race on a sun-streaked afternoon in mid-August. But that did not stop 300 union workers from taking to the streets of Hyde Park, carrying campaign signs and knocking on doors until dark.
They were hotel workers, nurses, and builders — not natural allies in terms of income, neighborhood, or line of work. But they showed up en masse that day for Martin Walsh, a state representative and former union construction worker who would come from behind and win more votes than any of his 11 rivals in the preliminary election.
That was only a taste of what labor leaders hope to deliver by Nov. 5. With the race now in full swing, and narrowed to Walsh and Councilor John Connolly, efforts to get out the union vote are ramping up. At least 40,000 union workers are registered to vote, from home health care aides to teachers, labor organizers estimate. That’s about 11 percent of total voters in Boston.
“We fought a really great fight, but we didn’t have everybody yet,’’ said Richard Rogers, executive secretary-treasurer of the Greater Boston Labor Council. “We’re going to really focus on union members that stayed home in the first round.’’
Today, 14.4 percent of Massachusetts workers carry union cards, according to the federal Bureau of Labor Statistics, the 12th highest percentage among the states. The figure is probably slightly higher in Boston, according to analysis by union officials for the Globe, who estimate that between 45,000 and 50,000 union members live in the city.
It’s a far cry from the 1950s, when one-third of workers were in unions. But the labor vote is still a factor, and some unions are growing in influence, in part because they have enjoyed Mayor Thomas M. Menino’s support. While the mayor has often become embroiled in high-stakes contract battles with unions representing police, firefighters, and teachers, he has championed private-sector workers, from nurses and tradesmen to lower-paid home care workers.
Perhaps the biggest surge in union membership and political influence is coming from Local 1199 of the Service Employees International Union, the largest health care workers union in the country, with 47,000 members in Massachusetts. It has 6,000 eligible voters in Boston, on par with the Boston Teachers Union.
Local 1199’s sway has grown considerably since 2007, labor leaders and political insiders say. It has added 22,000 home health care workers to its rolls and is engaged in initiatives that go beyond contracts, such as raising the minimum wage and rallying against MBTA fare hikes. And it is gaining a reputation for getting out the vote in communities of color in Dorchester, Roxbury, Mattapan, Hyde Park, and East Boston.
“They have a history of working on and winning campaigns,’’ Rogers said.
Beyond the sheer membership numbers, 1199 has developed an ability to rally support in neighborhoods that candidates find difficult to penetrate, thanks to energetic door-to-door campaigning, according to one Democratic operative, who spoke on the condition of anonymity because he did not want to offend other unions.
“They’re definitely the most sought-after union endorsement in the entire state,’’ he said.
By its own accounting, Local 1199 says it helped Elizabeth Warren win her US Senate seat, raising turnout in Boston by 7 percent and even more in Springfield and Lawrence.
Jim Stergios, executive director of the Pioneer Institute, a Boston-based think tank geared toward limited and accountable government, said that, beyond elections, there is little question unions have a big influence in Boston.
“For the longest time, the unions have had an inside track on decisions made across the city,’’ he said, citing the mayor’s challenges in negotiating with police and firefighters, as well as some teachers’ resistance to expanding charter schools.
But he does not necessarily expect a muscular union turnout in November, given the relatively low turnout in the preliminary on Sept. 24. Walsh reaped 20,854 votes overall, according to city election records, about 1,400 more than Connolly. Just 31 percent of the city’s registered voters cast ballots, or 113,319 people. Walsh took 18.5 percent of those votes.
Stergios said union money may be even more of a factor than votes. Unions have spent at least $917,000 on behalf of Walsh, according to the Office of Campaign and Political Finance. In addition to receiving direct donations from local unions, his mayoral bid has received support from such outside groups as Working American, an arm of the national AFL-CIO. A Virginia group funded at least in part by labor has paid for television ads for Walsh.
“They do have a huge influence in this on the money side,’’ Stergios said. In terms of voting, “we’ll see,” he said.
SEIU officials said their members’ support was spread across a number of candidates in the preliminary. But now that the union settled on a candidate, its leaders are pounding home their message.
“As health care workers, we know that Marty Walsh is a candidate we can trust,’’ said Veronica Turner, executive vice president of the 1199 SEIU United Healthcare Workers East in Massachusetts.
Part of the SEIU’s success has been tapping into a “big tent” version of unionism that goes beyond members. They helped the home care workers secure a wage increase of $1.64 per hour, to $12.48, as well as health benefits. But they are also inviting members to bring family and neighbors to meetings and to get involved in issues related to affordable housing, health care, public safety, and schools.
Susan Moir, director of the Labor Resource Center at the University of Massachusetts Boston, said it is easy for critics to boil down the impact of unions to a vote-getting strategy.
“During elections that’s the most visible function of the labor movement,’’ Moir said. “But you know, the labor movement doesn’t go away after elections. We work on social change.’’
Menino has backed efforts at bolstering workers’ standard of living, including unionizing health care workers and insisting on union contracts for big downtown development projects. But critics say he has faltered in dealings with the city’s big public unions.
In a his most recent contract confrontation, Menino decried an arbitrator’s decision to award the police patrolmen a 25 percent pay raise over six years, at a cost of $80 million that the mayor says the city cannot afford.
The question for many voters is whether Walsh’s union ties would make him a stronger or weaker negotiator than Menino. David Begelfer, chief executive of NAIOP Massachusetts, a commercial real estate developers’ association in Needham, said the business vote is split between those avoiding Walsh due to his union background and those wondering if it could be an advantage.
“Coming from that background and having relationships there gives him plausibly a unique ability to negotiate,’’ Begelfer said. “It doesn’t mean it’s not going to be difficult.’’
The city firefighters union has endorsed Walsh. Police unions have not backed a candidate. And the teachers union has no plan to endorse a candidate. But they still plan to influence the outcome.
“Our members are your neighbors. They live all over the city,’’ said Richard Stutman, president of the Boston Teachers Union. “They’re very active in the community, and we will have a say one way or another in who the next mayor is.’’
Andrew Ryan of the Globe staff contributed to this report. Beth Healy can be reached at Beth.Healy@globe.com.