Mr. de Blasio, however, can make the numbers jump even more with three specific steps.

1. He can deliver on his campaign promise to require that more affordable housing be built by organized labor. That will require some sort of deal to cut the cost of union workers. That might not deliver the savings, but that's what he promised. It is also one of the key issues as the big Queens residential project known as Astoria Cove speeds toward the City Council for approval.

2. He can require every new hotel to get a special permit, which would mean the City Council would have to approve them and would do so only when the developers agree the workers would be unionized. This has long been the dream of Peter Ward, head of the powerful hotel workers' union.

3. He can impose a similar requirement that new projects agree to hire unionized building-service workers. Even the Bloomberg administration did that frequently.

It is important to understand that the vast majority of the 811,000 people who belong to unions in New York work for government. But the influence of labor will be limited unless it can broaden its base. That's why labor leaders will pressure the mayor to fulfill his campaign promises and give private-sector unions a big boost.