Maryland Gov. Martin O’Malley scaled back one of his key environmental initiatives on Thursday as lawmakers said it became clear his controversial plan to curb sprawl faced an uncertain future with less than three weeks remaining in the General Assembly session.

O’Malley (D) had proposed giving the state power to override some local zoning decisions over new housing developments that rely on septic systems. The governor had said the state needed the authority to ensure it could reduce the waste that leaches from the developments and pollutes the Chesapeake Bay.

The governor’s plan, however, became a touchstone in a legislative session marked by power struggles between the state and counties over autonomy in school funding, teacher pension costs and development decisions.

On Thursday, O’Malley’s Cabinet secretaries for environment, planning and natural resources told a Senate committee they would support stripping out provisions that would have given final authority to the state to decide whether counties were abiding by master plan guidelines.

The retreat marked the second time in two years that O’Malley had weakened the proposal to try to win approval from the state legislature, which is controlled by Democrats.

O’Malley last year sought to prohibit construction of subdivisions of five or more houses built with septic systems. He said the downturn in the economy, when few houses were being constructed, was the right time for the state to establish such a strict law to protect the environment.

Several lawmakers said the changes made Thursday would take the teeth out of this year’s bill, giving counties the ability to draw mapped “tiers” of development to their liking and allow major subdivisions served by septic systems on farmland or forestland.

“If there are rogue counties that want to define tiers out of the spirit of what’s in the bill, the enforcement is problematic,” said Sen. Paul G. Pinsky (D-Prince George’s), a vocal proponent of the idea. “Look, I hope all the counties abide by the spirit of the law, but it falls on them.”

An administration official disputed characterizations that the bill would be feckless.

The bill “would have taken a pretty extraordinary measure of giving state control over local zoning,” the official said. “We decided, let’s get the policy implemented and not get stuck on who gets final say in how the map looks.”

But in a measure of how much the bill had changed, Republicans on the committee said they would be more likely to support it.

“I thought the amendments we made took it from a terrible bill to a bad bill,” said Sen. J.B. Jennings (R-Baltimore County). “I think these amendments make it a palatable bill.”

Staff writer Aaron C. Davis contributed to this report.