Portside

Hillary Clinton is racking up 2016 union endorsements, landing the support on Monday of a major national labor organization and a top public employee group in the first-in-the-nation primary state of New Hampshire.

The United Association of Journeymen and Apprentices of the Plumbing and Pipe Fitting Industry, which has 340,000 members, announced in a statement it would back the former secretary of State’s bid for the Democratic presidential nomination.

It’s the fourth national labor union to announce support for Clinton as she seeks to beat back a challenge from Vermont Sen. Bernie Sanders (I), who is aggressively courting the support of union workers.

In addition, the New Hampshire chapter of the National Education Association, which has 16,000 members, said Monday it will also support Clinton for president. The endorsement gives Clinton the backing of the biggest public employee union in a critical early-voting state.

Clinton is seeking to shore up her support in New Hampshire against a growing threat from Sanders, who has become the front-runner in recent polls of the Granite State.

A CBS News/YouGov survey released over the weekend showed Sanders with a 22-point lead over Clinton in New Hampshire. He has led in the four most recent polls there and opened up an 11-point lead, according to the RealClearPolitics average.

While Clinton has had early success in landing major union endorsements, many of the biggest labor organizations — including the AFL-CIO, the American Federation of State, County and Municipal Employees, the International Brotherhood of Teamsters, and the Service Employees International Union — remain on the sidelines.

Sanders has signaled he intends to fight Clinton for labor support.

He has won the backing of the National Nurses United, the nation's largest organization of nurses, and last week held a conference call with what his campaign said were “thousands” of union workers, urging them to pledge their support and campaign on his behalf.