Gov. Ned Lamont said that he will veto a controversial affordable housing bill – that his office negotiated – amid fierce protests from suburban towns.

The governor urged Connecticut lawmakers to craft “a better bill” for a special legislative session in September.

But when pressed, Lamont struggled to articulate what changes he wants to see.

For years, Lamont has complained about the lack of affordable homes. But on Monday, he said that a sweeping housing package passed last month goes too far.

“Reluctantly, I’m going to veto that,” he told reporters on Monday.

Lamont said that he can’t support the bill's “Fair Share” housing quotas. They would reward cities and towns that zoned for a minimum number of affordable units, but local communities could decide where to locate the housing and what it would look like.

The legislation did not include any penalties for violating “Fair Share” quotas, which – as part of a compromise – were 25% of what a consultant recommended.

“’Fair Share’ is make or break,” Lamont said. “If you’re going to dictate or suggest or imply a certain number of units, I don't think that’s going to work for me.”

Over the past few weeks, opponents mounted an intense campaign urging Lamont to veto House Bill 5002.

“One of the sections that they worried about, and I did as well, is what they call ‘Fair Share,’ where sort of outside consultants came in and told towns this is the amount of housing you have to have town-by-town,” Lamont said.

The housing package also eliminated parking requirements for smaller apartment complexes and made it easier for developers to convert commercial buildings to smaller residential units.

Beyond zoning, the bill also included new protections for renters, including a ban on landlords using algorithms to set rental rates.

Affordable housing groups were stunned by Lamont's announcement. After all, they negotiated this bill with his staff.

“We are profoundly disappointed,” said Erin Boggs, with Open Communities Alliance. “It was really kind of stunning that at the 11th hour we have an objection to this that appears to be based on misinformation.”

Advocates were confused by Lamont's rationale.

“The things that the governor said he's looking for in a housing bill are what is in 5002,” said Open Communities Alliance policy director Hugh Bailey.

Housing groups have pushed for zoning reform for years, arguing that some towns make it nearly impossible to build new multi-family housing.

“Thousands of working-class and middle-class people can’t afford to rent or own a home in Connecticut, making this veto disappointing and short-sighted,” said Melvin Medina, with The Connecticut Project Action Fund. “We hope that the next housing bill makes significant progress in enabling working-class and middle-class people to afford to live here.”

The state needs at least 150,000 new units, according to a new study from the Connecticut Business and Industry Association. The shortage costs the state economy billions, CBIA found.

But suburban towns are celebrating a victory. They called the housing bill a free pass for developers.

“This is one the biggest attacks on local control of decision-making, including zoning and housing, in a generation,” said state Sen. Ryan Fazio (R-Greenwich).

Municipalities said the proposal was too heavy-handed.

“The fair share language in the bill, which is modeled on a New Jersey law that has been mired in lawsuits, would subject municipalities to burdensome and confusing top-down housing mandates,” said Betsy Gara with the Connecticut Council of Small Towns. “Moreover, the bill dictates a municipality’s fair share housing allocation based on a flawed methodology that fails to consider critical factors, including a town’s percentage of buildable land, proximity to jobs, access to transportation, and water and sewer capacity.”

The group CT169Strong led the opposition.

“There was no misinformation,” the group said in a statement. “Over the past several weeks, the Governor has heard from thousands of Connecticut residents from almost every town in the State as well as the bipartisan voices of locally elected mayors and first selectmen, land use and other officials.”

Some Republicans believe they can find common ground on reforms to 8-30g, the decades-old law that allows developers to sidestep local zoning in towns that don’t have enough affordable units. Both sides agree that the law has failed to bring housing costs down.

“I promise to work towards a bipartisan solution,” said state Rep. Tom O’Dea (R-New Canaan). “This bill – 5002 – was not bipartisan.”

Lamont asked lawmakers to craft a new housing package for a special session this fall.

So how would it be different?

The governor couldn’t really say when asked, referring to the “Fair Share” quotas they he rejected in his veto.

“If you don’t want to come up with a plan, there’s a ‘Fair Share’ group that’s hired a consultant. They’ve looked at what they think is a reasonable number of units for you to consider,” Lamont told reporters. “So if you don’t want to step up, we’ll step up on your behalf.”

Majority Democrats hold enough seats in the General Assembly to override Lamont’s veto, but they would need almost all their members to agree. Eighteen Democrats – mostly from Fairfield County – voted against the original legislation.

Lamont recently said he is leaning toward running for a rare third term.