Despite objections from non-union contractors, the Los Angeles County supervisors on Tuesday approved a union-backed project labor agreement for construction of a $95 million ambulatory care center on the Martin Luther King Jr. Hospital campus in Wilmington.

The agreement, one of the first imposed on a major county project, requires all construction contractors to hire workers through union-run hiring halls and pay into a special fund for workers’ benefits. In exchange, the Building Trades Council of Los Angeles and Orange Counties pledged “labor peace,” meaning no strikes or other job actions.

The board’s 3-2 vote came after months of contention as non-union contractors said the agreement would effectively shut them out of the lucrative project. Non-union contractors objected to provisions requiring them to hire locally through the union halls. They also objected to having to pay into the workers’ benefits fund when many contractors already pay benefits to their workers.

Earlier this year, L.A. County Supervisor Gloria Molina had raised concerns about this benefit payout requirement, leading non-union contractor representatives some hope that the agreement would be altered. She also wanted to give non-union contractors more of a voice in the negotiations between the county and the building trade unions.

But in the end, Molina supported the agreement, providing the crucial swing vote.