The state's contentious affordable-housing law, up for repeal by voters in the Nov. 2 state election, has generated more than $9.25 billion in construction and related spending over the past 10 years, according to a study scheduled to be released Wednesday by the University of Massachusetts Donahue Institute. The report, commissioned by a nonprofit group that supports the 1969 law known as Chapter 40B, also found that more than 21,000 housing units that are part of planned 40B developments would result in more than 54,300 jobs and another $10.42 billion in spending. Aaron Gornstein, executive director of the Citizens' Housing and Planning Association, which commissioned the study, hopes its findings will help persuade voters to reject Question 2, one of three ballot initiatives this fall. 'It demonstrates the significant economic impact that affordable housing has had in the Commonwealth,' Gornstein said. 'It is one of the important reasons to make sure it does not get repealed.' The law allows builders to bypass certain zoning restrictions in municipalities where less than 10 percent of the housing stock is classified as affordable. To win the waivers, they must set aside 20 to 25 percent of the units in a development for residents who make less than the community's median income and offer those homes at below-market rates. Opponents say the law allows developers to bully local officials into approving housing that violates building codes and inflates housing costs, because market-rate units are priced higher to subsidize so-called affordable homes. Jon Witten, a Duxbury lawyer and law professor, said the UMass study points out the obvious: that Chapter 40B is an economic engine that creates housing. But he added that many critics of the law are not opposed to development; they want an affordable-housing program that does not circumvent the best interests of communities. 'When you erase all rules and regulations at the local level, the result will be housing' - but nothing more, said Witten, who teaches law and land-use planning at Boston College and Tufts University. 'The majority of other states have found a far more efficient way of building affordable housing that doesn't benefit only the developer.' Advocates of 40B say it has been key to providing much-needed affordable housing in a state where real estate has historically been more expensive than in most other regions. The UMass study is part of a growing campaign to fight the repeal, a movement that the law's supporters say has the support of 1,000 people and organizations - including political, environmental, and religious groups. This year, they have raised more than $524,000, of which about $185,000 has already been spent, including on private consultants, Web designers, and paid organizers. According to a State House News Service poll released last week, their efforts appear to be working. The survey of 400 voters found that 56 percent plan to vote against the repeal, with 36 percent in favor of it, and 10 percent undecided. Still, Gornstein said, 'We are taking nothing for granted. There is nothing more important right now. It is the future of affordable housing.' The committee hoping to repeal the law has raised only $5,000, according to the most recent campaign reports. John Belskis, chairman of the Coalition to Repeal Chapter 40B, said opponents of the law are made up of residents in 284 communities. Supporters include developers, real estate brokers, and affordable-housing advocates who profit from special permitting allowed under 40B, Belskis said. 'People are lining their pockets,' he said. 'I call it the poor people's industry.' Advocates of the law, however, say the study is one more reason to support a process that has created 80 percent of the affordable housing in smaller towns and cities over the past decade. Rachel Bratt, a professor of urban and environmental policy and planning at Tufts University who is studying affordable housing laws, said Massachusetts is seen as a model by many. 'I'd argue what we have done here is pretty innovative, pretty bold, and very successful,' she said. The study found that 21,861 housing units, including 8,140 affordable homes, have been built since 2000, creating significant spending and nearly 48,000 jobs. Another 21,078 homes, including 6,119 classified as affordable, are in various stages of planning, the study said. The report's authors said some of the housing might have been built without the law, but it's likely the vast majority would never have broken ground. More than a third of rental housing built in the state over the past 10 years has been created through Chapter 40B, said Lindsay Koshgarian, a Donahue Institute research manager. Koshgarian also said the law does not inflate property costs because developers save money throughout a streamlined permitting process and affordable housing receives state and federal subsidies. 'It is letting developers build affordable housing because they get to save money during the process,' she said. 'Chapter 40B has been a major outlet for developers to be able to build housing in the state.' 