Gov. Deval Patrick is expected this week to sign a bill requiring the state to post on a quarterly basis the workforce diversity of contractors working on public projects. Supporters say the bill aims to hold contractors on state-funded construction efforts accountable.

“As we see frequently today, bidders will often make very nice sounding commitments to the state and the neighborhoods in order to get the bid, or at the beginning of the contract about how much local hiring they’re going to do,” said state Sen. Sonia Chang-Diaz, a Jamaica Plain Democrat who represents parts of Dorchester and Mattapan. “And then we’ll see that the project will end and they didn’t come anywhere near those numbers.”

Chang-Diaz said the bill will allow watchdogs and members of the public to see contractors’ hiring of local residents and people of color closer to “real time,” instead of at the end of the work.

The state’s budget office will post the performance numbers on a website, contract by contract.

The bill, S2386, requires state agencies handling construction bids to evaluate bidders’ past performance on workforce diversity and includes diversity goals in state-funded construction projects.

Chang-Diaz said the numbers are often difficult to obtain. “Sometimes I have to ask six or seven times to get numbers, and I’m a state senator,” she said.

State Rep. Linda Dorcena Forry, a Dorchester Democrat who worked on the bill in the House, said the law isn’t going to force contractors to employ people of color, but their metrics should be available to the public. The bill, which was passed in the waning days of 2012, will not mean more work for contractors, she contended. “You submit quarterly information anyway; here’s an additional graph to fill out,” she said.

Chang-Diaz said she views the website that will be set up as a “giant crowd-sourcing project,” with citizen watchdogs possibly tracking the diversity numbers. “There are not enough resources in state agencies to be doing the kind of real close watch-dogging, real bean-counting to ensure each project” meets diversity goals, she said.

The city of Boston has guidelines, known as the Boston Residents Jobs Policy, for city-hired contractors, suggesting that 50 percent of workers on job sites be Boston residents, 25 percent minorities, and 10 percent women. Councillors, including Ayanna Pressley (citywide) and Michael Ross (Mission Hill), have pushed for more transparency in the hiring data.

In a statement, the chair and vice chair of the Massachusetts Tradeswomen’s Association, Jenaya Nelson and Katie Liljegren, called the Senate bill a “good win. To be blunt, without this bill, there is no incentive for contractors to hire tradeswomen; but without enforcement of this bill, there will be no incentive in training or hiring tradeswomen on the next job and the next,” they said. “And so, there is still work to be done. We look forward to that large task and are encouraged by this victory.”