On a sweltering afternoon in July, affordable-housing advocates, religious leaders, and some of New Jersey's most influential officials arrived in Mount Laurel for a celebration years in the making.

The Legislature and Gov. Corzine had closed what those gathered saw as a loophole in the laws requiring every New Jersey town to provide homes for people with low and moderate incomes.

The ceremony took on the air of a joyous tent revival.

Six months later, the groups that enjoyed that day are on the defensive, and one senator who helped make the July bill-signing possible has become one of the affordable-housing system's sharpest critics.

Sen. Raymond Lesniak (D., Union), the Senate sponsor of the bill that closed the so-called loophole, has joined a chorus of lawmakers and mayors calling for delaying towns' latest plans to provide affordable housing. The move would create another delay in a planning process stalled for nearly 10 years.

Lesniak and others say that at a fragile economic time when jobs are needed, the state's complex housing mandates will choke off projects.

"The world changed when the economy collapsed in September," Lesniak said.

He said he does not oppose low-cost housing but wants changes in the methods set by the Council on Affordable Housing.

"COAH has been a failure in promoting affordable housing during good economic times. Its strangulation type of regulations will do nothing to promote affordable housing and will stifle any other development" in bad times, he said.

Republicans have been making that argument for years, but now some Trenton Democrats are adding political power to the cause.

Lesniak plans to introduce a bill today that would revamp parts of the state's affordable-housing laws. It is expected to include new ideas for paying for the housing requirements, possibly including tapping the state's debt-reduction fund or using money from a hoped-for federal stimulus package. He said $10 billion is needed over the next 10 years to pay for the housing mandates.

While a court has rejected mayors' case for pushing back the deadline for affordable-housing plans, a pending piece of legislation could provide the legal rationale needed for the Corzine administration to permit a delay.

The latest housing requirements, calling for 115,000 new low-cost units by 2018, were set earlier this year after nearly a decade of setbacks and legal challenges. The obligations were first due in 1999. Unless an extension is granted, towns have until Dec. 31 to submit plans for their shares of affordable housing.

At stake, according to housing advocates, are homes that give people with low incomes the chance to move into communities they normally couldn't afford, giving them access to better schools and safer neighborhoods.

Kevin Walsh, associate director of the Fair Share Housing Center in Cherry Hill, is among those who fear that another delay will open the door for scaling back the inclusionary housing rules set in a series of Supreme Court cases based around Mount Laurel.

"Really what's going on is towns are more opposed than they used to be to providing housing for the folks who work in the town, who pour the coffee, who pick up their garbage," Walsh said.

Critics of the state's affordable-housing laws say their argument is about realistic limitations. They say the current system - which requires towns and builders to add a portion of affordable-housing units with every new housing or commercial development - is too costly and complex for towns to have plans in place by year's end.

"The methodology has to be redone, the funding source has to be identified," said Sen. Christopher Bateman (R., Somerset). "If we're going to do it, let's do it right."

The bill signed in July banned deals that let some towns pay others to build a portion of their affordable-housing requirements. Mayors said the change left them with fewer methods to meet new requirements, which they argue are inflated by faulty state planning.

The new law also included a statewide 2.5 percent development fee intended to help towns pay for new housing. Builders favored the charge over the patchwork of local fees that had existed, but Lesniak said it is an added burden in difficult times. He hopes to eliminate it.

Mayors say that without financial help they will be forced to raise property taxes to pay for schools, sewers, and other infrastructure associated with new housing. In a court case to block the new requirements, they say the latest obligations could force towns to build on some of their last remaining open spaces.

In the face of these concerns, Bateman and Lesniak have called for a six-month extension of the deadline for all towns to submit their latest affordable-housing blueprints. Assembly Speaker Joseph J. Roberts Jr. (D., Camden), a fighter for affordable housing, last week added a key voice those seeking delay, saying towns should be allowed to apply for 90-day extensions.

"We are taking recommendations regarding a deadline extension under consideration," Department of Community Affairs Commissioner Joseph Doria said through a spokesman. "The most important thing is that we start providing the affordable housing that is not only our moral obligation, but also, as outlined by the courts, our constitutional one as well."

Doria said more than 200 towns, about a third of those in the state, have signaled they are ready to submit plans by the deadline. Towns have had since early June to make plans, according to the Department of Community Affairs.

The agency notes that since the housing requirements are based on growth, towns are not required to supply more units if there is no development.

Roberts said it makes sense to give mayors time to develop careful plans, but he did not expect the state to back away from its mandates.

"We cannot retreat from our commitment to make sure that housing opportunities exist for working families in New Jersey," he said.

Contact staff writer Jonathan Tamari at 609-989-9016 or jtamari@phillynews.com.