CHARLESTOWN — All options are still on the table, from status quo to a full withdrawal from the Chariho Regional School District, even establishing a privately managed school district.

But given Hopkinton’s vote this week officially objecting to a new school building proposal –– probably derailing the plan that district officials had pitched as a last-ditch effort to capitalize on state aid that might be slashed given the state’s financial crisis –– the withdrawal options are gaining momentum.

“This is not a group that is anti-Chariho,” Richard Hosp, the vice chairman of Charlestown’s ad hoc withdrawal update committee, said yesterday.

“This is a group that feels that feels that we are being pushed into this [withdrawal] by some really unreasonable requests.”

The request: Hopkinton’s insistence that Charlestown agree to tax equalization, which would probably more than double Charlestown’s share of the Chariho budget.

(Talk of tax equalization has toned down in Richmond, which pays the highest share, at 36.03 percent.)

Hosp, who chairs Charlestown and Chariho’s finance committees, estimated that establishing its own school district would cost Charlestown nearly $3 million a year. Tax equalization, he said, would cost in excess of $7 million if the towns pool their state aid, $12 million otherwise.

Currently, state aid goes directly to the towns, which then apply it to their portion of the school district’s budget.

Moreover, Hosp said, all of the state’s regional districts –– Bristol Warren, Exeter-West Greenwich, Foster-Glocester and Chariho –– are funded on a per capita basis.

“It’s uneconomic for us to do that,” Hosp said of tax equalization. “For far less money, we think we could build a superior school system.”

Committee members said their goal was to form a “world-class educational institution” –– within or outside the Chariho Regional School District.

The seven-member committee is expected to present its preliminary report to the Town Council on June 9, including cost estimates of building its own schools –– updated figures prepared by Newport Collaborative Architects for the town’s 2004 failed withdrawal effort.

That plan would provide the backbone of a withdrawal plan –– if the committee ultimately decides to recommend that course to the council.

If so, Charlestown would proceed with a two-phase construction plan, giving room for adjustment given the town’s falling student-age population.

Mirroring the 2004 plan, the first phase would entail renovation of the existing elementary school to house pre-kindergarten through fourth-grade students and building a fifth- to eighth-grade middle school followed by the construction of a high school in phase two.

High school students would attend other districts or private schools on a tuition or voucher basis.

Construction could begin in the spring of 2010.

Committee members are considering various locations, including the preferred locations from the two previous withdrawal proposals –– Ninigret Park, a 25-acre portion of an open space site near Town Hall on Route 2, and a private lot at Route 1 and Kings Factory Road, currently subject to a controversial residential proposal called Ninigret Hamlet.

Ninigret Park remains the top choice.

The former Navy airfield, committee members said, would be the most central location for schools. It would fit into the park’s master plan that is currently being drafted and benefit from the existing sport fields.

Concerns remain over possible contamination and site constraints that would prevent any of the buildings from being certified as hurricane emergency shelters. Currently, the only hurricane shelter approved in the area is the Chariho Middle School.

“Charlestown as a town is really in a position where we have an opportunity to provide our students an excellent education,” said Giancarlo Cicchetti, the committee’s chairman who also serves on the Chariho Regional School Committee.

“We can afford to provide a good education to our kids. We would like to provide an excellent education.”

marmenta@projo.com