Breaking news-
Hillary Clinton has received the endorsement of the International Association of Bridge, Structural, Ornamental and Reinforcing Iron Workers (generally shortened to Ironworkers) today.
Why Hillary (and not someone else?)
...several other candidates align with ironworker values, none compare to Secretary Clinton when it comes to putting those beliefs into practice. Clinton’s record of looking out for the jobs that union members rely on was the largest factor in the council’s decision. Her support for workers’ rights, infrastructure investment and economic opportunity lines up with the union’s priorities for the next administration. Secretary Clinton’s unmatched experience in government will enable her to deliver on her promises in ways the other candidates cannot.
There is also a connection from Hillary’s time in the Senate and the priorities she fought for then
The Secretary was tested as soon as she entered the U.S. Senate by the terrorist attacks of September 11, 2001. Then-Senator Clinton sponsored legislation to provide for the ironworkers and others who sacrificed their health rescuing victims and clearing rubble on “the Pile” in New York and the Pentagon in Virginia.
On Clinton’s commitment to combat the threat of climate change and protect American workers
With many jobs connected to the energy and manufacturing sectors, ironworkers are directly affected by new regulations on greenhouse gases and other environmental issues. In the union’s assessment, other candidates for president have either unconstructively denied climate change or shown a cavalier attitude towards jobs lost due to environmental regulation. The union expects Clinton to take a balanced approach, protecting the public from pollution while keeping Americans at work building the economy.
What is at stake
Besides the president, voters across the United States will choose 12 governors, 34 senators, and countless state and local officials. With right to work legislation on the march in states throughout the country, 2016 is a vital year for ironworkers to make their voices heard.
http://www.ironworkers.org/press-room/2015/11/23/iron-workers-endorse-hillary-clinton-for-president
The Union has a national membership of about 125,000 workers. In 2008, they endorsed Barack Obama in June, after the primaries had concluded.