In accepting the endorsement of eight building trades unions Wednesday night, John O'Neill, a Democratic candidate for district attorney, vowed to help the unions by creating a labor liaison position in the District Attorney's Office.

"A district attorney's office that supports labor, that works with labor, is a district attorney that works with and for Philadelphia," O'Neill said to more than 200 workers at the Plumbers Union Local 690 Hall in Northeast Philadelphia. "As your district attorney, as one of my first acts in the first 30 days, I will appoint a deputy of labor liaison."

Applause broke out among the crowd, which included members of the Sprinkler Fitters,  Ironworkers, and Communication Workers unions. O'Neill said the position would exist "so that every one of you will have direct and constant communication with a person who understands what you need and who sticks up for you."

O'Neill, 35, worked for 10 years as an assistant district attorney before deciding to run for the top post. He was one of the last of the seven Democratic candidates to throw his hat in the ring. He also came second to last in the first round of fund-raising.

Wednesday night's endorsement was significant, because he will now have an army of union workers raising money on his behalf and sending campaign literature to voters endorsing him. But whether that will give him a lead in a race without an incumbent or the local Democratic Party making an endorsement remains to be seen.

Other candidates have received big endorsements, including former Managing Director Rich Negrin, who was endorsed by the Fraternal Order of Police, and  civil-rights lawyer Larry Krasner, endorsed by the local health-care workers' union. Krasner is also receiving outside help from a political action committee backed by billionaire George Soros.

Nevertheless, O'Neill said he felt confident Wednesday night.

"This means everything," O'Neill said after the rally. "To have this level of support … is humbling, inspiring. I can't even put it into words."

Asked if the endorsement and his decision to implement a labor liaison position were signs that O'Neill is already too close with the unions, he said that was not true, noting that unions provide training and jobs to many Philadelphians.

"Good-paying jobs need someone supporting them. When you have a situation, for example, where someone illegally classifies a job the wrong way so that they can rip off their workers or so that they can avoid paying things the law requires them to pay, it only makes sense to have a DA's Office that supports the law," he said.

"Nobody puts people on the street like we do," Miller said.  "You're not going to get elected unless you have the building trades behind you."