In what appears to be organized labor's first foray into the nascent race to succeed U.S. Rep. Edward Markey, the Central Massachusetts AFL-CIO is backing state Senator Karen Spilka in her bid for the seat.
"She's been someone that we have had a very good relationship with over the years," said Joseph T. Carlson, president of the Central Massachusetts AFL-CIO.
The organization, whose territory includes Spilka's senate district west of Boston, is one of the Massachusetts AFL-CIO's 10 regional councils.
The councils do not have the power to issue formal endorsements themselves.
But Central Massachusetts — one of two AFL-CIO councils in the Congressional district — is formally recommending that the statewide union endorse Spilka in the Democratic primary.
Spilka is one of at least five Democrats vying to replace Markey should he defeat Republican Gabriel Gomez next week in the special election to replace former U.S. Sen. John Kerry.
The other declared candidates include Middlesex County Sheriff Peter Koutoujian, of Waltham, state Sens. William Brownsberger of Belmont and Katherine Clark of Melrose, and state Rep. Carl Sciortino of Medford.
State Rep. Sean Garballey of Arlington has floated his name. And former state senator and gubernatorial candidate Warren Tolman tells WBUR he is also considering the race.
Observers and union officials say the labor movement will probably not coalesce behind a single candidate.
"I think it's really tough for us," said Harris Gruman, executive director of the politically savvy Service Employees International Union Massachusetts State Council.
Gruman said that, of the declared candidates, Spilka, Clark and Sciortino have all been friends of labor in the state legislature.
Various local SEIU unions, he said, may go their own way in the race.
The AFL-CIO has not been the picture of unity of late, either. The statewide union split in the U.S. Senate Democratic primary pitting Markey against U.S. Rep. Stephen Lynch — endorsing neither candidate in the end.
And if the Central Massachusetts council has backed Spilka in the U.S. House contest, the other AFL-CIO council in the Congressional district -- the Greater Boston Labor Council, which is larger — has not weighed in yet.
The brewing race has been relatively low key, to date, with candidates wary of distracting public attention from Markey's Senate bid — or looking too presumptuous about him winning.
But there has been plenty of activity behind the scenes, with campaigns raising money, hiring staff and consultants and looking to shore up support with business, labor and other interest groups.
Clark, for instance, has won the endorsement of several key women's activists.
The Women's Campaign Fund, a Washington-based non-partisan group that donates money to women candidates through a political action committee and encourages a national donor base to give, has endorsed Clark.
And Emily's List, which raises money for pro-choice Democratic women, has put Clark "on the list" — encouraging its own donor network to give to her campaign.
That's one step below a formal endorsement. And the Spilka campaign confirms that it has lobbied Emily's List to put her "on the list" too — enlisting some prominent elected officials in the effort.
Emily's List did not return several calls for comment.
Barbara Lee, a Cambridge philanthropist who works to elect women around the country and is backing Clark, said the candidate's early fundraising strength gave her an edge among activists.
"Our research shows that women need to be prepared so that they have that infrastructure and are ready on day one," said Lee.
Clark, a former prosecutor, collected nearly $262,000 in the first quarter of the year, according to campaign finance filings. Spilka, a labor lawyer, started raising money later.
Carlson, of the Central Massachusetts AFL-CIO, said there was no single effort that won Spilka the group's support — pointing, instead, to her long history of supporting union causes in the legislature.
But her geographical ties to the group played a role, too. And it is the state senator's regional strength that may be her chief asset in the campaign.
The Fifth Congressional District bends around Boston from the north to the west. And while the other four declared candidates are bunched up in the northern suburbs, Spilka has the western part of the district to herself.