BOSTON — Environmental activists are assembling a $5 million effort to support Sen. Edward Markey's re-election bid, while organized labor factions were quick to line up behind Rep. Joseph Kennedy III after he formally joined the Senate race on Saturday.

On Sunday, Kennedy announced endorsements from IBEW Local 103, Teamsters Local 25 and the Massachusetts State Council of Machinists.

Kennedy is pressing the theme of "moral capitalism" early in his campaign. "There is no greater fight in this country today than for the working men and women our economy has left behind," he said in a statement. "For generations, American unions have served as a firewall between workers and abuse, exploitation, and injustice. I'm proud to carry this fight in my campaign and to center the voices of working people in the weeks and months ahead."

Meantime, Environment Massachusetts announced late Friday that it is reaching out to groups and individuals in Massachusetts to urge them to make donations to an independent expenditure campaign. The goal is to amass $5 million and the Environment America Action Fund has pledged $1 million.

"We are lucky to have one of the nation’s strongest climate champions, Ed Markey, representing Massachusetts in the U.S. Senate. Voters need to know what Ed Markey has done throughout decades of public service to advance renewable energy, clean water, clean air, and the protection of our public lands. We intend to tell his story," Ben Hellerstein, state director for Environment Massachusetts, said in a statement.