SHIRLEY -- At a full house at the Finance Committee meeting Tuesday night, Chairman Mike Swanton said he can't see any way Shirley can pay its school assessment as presented.

The meeting included the Ayer-Shirley Regional School District Superintendent Carl Mock, the business manager and School Committee representatives.

Based on the School Committee budget, Shirley's share of the annual assessment came in 8.6 percent higher than last year. But Town Administrator Patrice Garvin built a 4.88 percent increase into the municipal operating budget, which started out with a $300,000 deficit and is still in the red, despite cuts that included one layoff, a reduction in staff hours and anticipated changes in the employee health-insurance design plan.

The school district produced a needs-based budget for fiscal 2015 that Mock said is barely enough to sustain services and continue to improve education. But Garvin said two new positions were added: a high-school special-education teacher and an elementary-school classroom teacher.

In a paper explaining the "preliminary budget" in terms of school district needs versus member towns' ability to pay, Mock said this year's requests for additional resources reflect "unmet needs" for the previous two years, and the needs deficit continues to grow.

But Swanton said the schools can certainly push for the higher number, even if it calls for a tax override, but he doubts such a proposal would fly, with the high-school building project slated to raise town property taxes in the coming fiscal year, adding about $170 to the tax bill for an average single family home valued at $250,000.

Swanton said he wanted to pose three questions to district officials. First, what's the implication of a regional budget that comes closer to the town's affordable benchmark? What drives the "significant increase" this year's school budget represents? Are we making headway on the Choice-in versus Choice-out balance to tilt it toward rather than away from the district? One of the promised perks of regionalization was stemming the costly choice-out flow of students leaving the district, he said.

"We understand it's a lot to ask," Mock said as discussion turned to $500,000 worth of items on the district's educational wish list, a couple of which made the final cut, including a $72,000 add-in for a high-school special-education teacher. The position is essential, he said, as is a new classroom teacher for Page-Hilltop Elementary School.

Without the special-ed teacher, a targeted group of high-school students would likely require placements that would cost the district much more, including transportation. As for the elementary-school classroom teacher, previous intra-district moves postponed the need for a new hire, but it's critical now and if the position is not added, class sizes will increase, Mock said.

Swanton suggested revisiting the need for assistant principals at the elementary-school level, which Mock staunchly defended.

Mock insisted the budget is realistic and that if any items other than those two were added, two other items would have to come out to pay for them.

"I know you have a figure," he said, addressing Swanton and Garvin, but without cutting personnel or shortchanging transportation so that buses would no longer pick up younger students who live within the 2-mile limit set by the state. "There's no other way," he said.

Swanton said the real problem is lack of new revenue, which brought him back to the School Choice dilemma. Three years into the new region, he asked why the tide hasn't turned in the district's favor.

School Committee member Susan Therriault said that was an unrealistic expectation.

"It's a long-term proposition," she said.

Suggesting other towns do better than Shirley or Ayer in terms of their contribution to schools is not accurate, Garvin said. "This town pays 50 percent of its budget for schools," he said. He added that home values are higher in those communities.

Conversation strayed into areas neither side could do anything about, such as how the district can better market the new high school on Washington Street in Ayer and how the town can help draw down its deficit via "tax title" to recoup unpaid property taxes.

The groups plan to convene again at next week's selectmen's meeting.