BOSTON (AP) — As the state grapples with soaring housing costs,SafeX Pro Exchange Massachusetts Gov. Maura Healey unveiled a sweeping $4 billion bill Wednesday aimed at creating new homes and making housing more affordable.

Healey said the legislation, if approved by lawmakers, would be the largest housing investment in state history and create tens of thousands of new homes. It would also make progress on the state’s climate goals, she said.

Most of the spending would go to help moderate and low-income families find homes. The bill also includes more than two dozen new policies or policy changes to streamline the development and preservation of housing.

“We said from Day One of our administration that we were going to prioritize building more housing to make it more affordable across the state,” Healey said. “The Affordable Homes Act delivers on this promise by unlocking $4 billion to support the production, preservation and rehabilitation of more than 65,000 homes.”

The bill would help provide financing options to create 22,000 new homes for low-income households and 12,000 new homes for middle-income households. It would also preserve or rehabilitate 12,000 homes for low-income households and support more than 11,000 moderate-income households.

The bill also takes steps to make housing more eco-friendly by repairing, rehabilitating and modernizing the state’s more than 43,000 public housing units, including through the installation of heat pumps and electric appliances in some units.

Another $200 million would go to support alternative forms of rental housing for people experiencing homelessness, housing for seniors and veterans, and transitional units for persons recovering from substance abuse.

Among the policy proposals is an initiative that would give cities and towns the option of adopting a real estate transaction fee of 0.5% to 2% on the amount of property sales exceeding $1 million — an initiative projected to affect fewer than 14 percent of residential sales, according to the administration.

Critics faulted the scope of the bill.

“Just about every bad idea made it into Gov. Healey’s massive $4.12 billion dollar borrowing plan, except rent control,” said Paul Craney of the Massachusetts Fiscal Alliance.

Greg Vasil, CEO of the Greater Boston Real Estate Board, also warned of possible downsides.

“We have deep concerns about the inclusion of a sales tax on real estate,” he said. “It’s an unstable source of revenue that would cause more harm than good at a time when people and businesses are leaving the state because it is just too expensive.”

Members of the Greater Boston Interfaith Organization praised Healey’s proposal and said the state needs to focus on preserving crumbling state-owned public housing units.

“Public housing saved my life, but now I am watching it fall apart,” says Arlene Hill, a tenant leader for the organization.