By Amanda Becker
WASHINGTON (Reuters) - The labor organization representing the U.S. building trades on Thursday endorsed Democratic presidential candidate Hillary Clinton, giving her the backing of national labor groups that represent more than 11 million workers.
North America's Building Trades President Sean McGarvey praised a $275 billion infrastructure plan Clinton announced this week as "robust, yet entirely practical."
The building trades group is an alliance of 14 unions that represent 3 million skilled craft professionals. One of its member unions, the International Heat and Frost Insulators, endorsed Clinton this week.
Insulators President James McCourt, in a letter to Clinton seen by Reuters, praised her "recognition of the significant contributions of our members to energy efficiency."
Clinton said in a statement to Reuters: "I am honored to receive the endorsement of the Insulators Union, whose leadership in energy efficiency is essential to making America a clean energy superpower."
She now has the backing of 16 individual unions, along with the building trades alliance, that collectively represent more than 11 million workers. Roughly 14.6 million workers - about 11.1 percent of the workforce - are union members, according to U.S. government data.
Some of Clinton's endorsements include influential unions such as the AFSCME, a public employees union with 1.6 million members, and the Service Employees International Union, or SEIU, which has about 2 million members in a variety of professions that range from nursing to janitorial services.
The building trades group and the 30,000-member insulators union are both affiliated with the AFL-CIO, a federation of 56 labor unions that collectively represent more than 12 million workers.
The AFL-CIO has not yet endorsed a candidate and has not traditionally done so in recent presidential elections until the party-nominating contests are nearly decided.
Endorsements by national unions do not prevent their rank-and-file members from supporting a different candidate, such as Clinton's chief rival for the Democratic presidential nomination, U.S. Senator Bernie Sanders of Vermont.
But the fact that Clinton has secured such a large portion of organized labor's support ahead of the first nominating contests in February shows the momentum she is gaining ahead of the general election in November 2016, when union workers are traditionally important on-the-ground foot soldiers for Democratic candidates.
Clinton's emphasis this month on jobs, and infrastructure in particular, is a move to woo working-class voters, who will be critical to winning the general election.