First Selectman Tim Herbst is warning department heads to brace for potentially devastating budget cuts if the state follows through on Gov. Dannel Malloy’s proposal to strip millions of dollars in state funding from suburban towns.

The proposed reductions, in the form of eliminating the town’s education grant and requiring the town to assume about one-third of the cost of teacher pensions, could top $6 million. Closing that funding gap would require a tax hike of about 6%, Herbst said.

“In all good conscience, I cannot and I will not support a tax increase of 6%,” Herbst said. “The citizens of Trumbull cannot afford this kind of increase.”

In a memo to all town employees last week, Herbst said he had asked all department heads to submit contingency budget proposals for next year. The plans are to show the effect of a 5% reduction from current levels, and a 10% reduction.

Herbst also requested a breakdown of the effect a $3.4-million cut would have on the school budget.

Herbst predicted that the effects of such cuts in town departments would likely include furlough days for town employees, reductions or eliminations of senior tax relief and leaf pickup programs, and a reduction in library services and operating hours.

“I say this not to alarm, but to underscore how we must work together to mitigate Governor Malloy’s proposed budget reductions while still providing the highest level of service to our citizens,” Herbst wrote. “I am turning to you for recommendations and feedback.”

The potential cuts to the school budget are likely to be the most contentious, but given that two-thirds of the town’s annual spending goes to the schools, is unavoidable, Herbst said.

State law prohibits municipalities from reducing the annual budgets for education. A town may reduce, or even eliminate, a requested budget increase, but may not provide fewer dollars than the schools received in the previous year.

Herbst, though, said in conversations with other town officials that he thinks that rule could be nullified if the state went as far as to eliminate the $3.4-million Educational Cost Sharing grant for Trumbull.

“My understanding is if our ECS share is zeroed out, we can go below the current budget,” Herbst said. Such a move, though, is likely to be challenged in court.

Further complicating matters is the fact that Trumbull currently is in the middle of its budget process and is slated to finalize the 2017-18 budget next month. The state, though, won’t complete work on its budget until June.

“We’re in uncharted territory,” Herbst said. “We have to pass a budget before we know what the state will do. We have to prepare for the worst, and I don’t know how we can say we’ll leave the [state funding estimate] number as is. But what’s the alternative?”