PORTLAND – A $500,000 line of credit secured by an anonymous benefactor from Tennessee would fund the start-up costs of a charter school proposed in Portland.

Supporters of the Baxter Academy of Technology and Science say that loan should assure state officials that the school would be on sound financial footing when it opens in September.

Critics say the loan from SunTrust Bank of Knoxville, Tenn., obtained just two weeks ago, shows desperation and raises questions about the validity of the school’s financial plan. They are urging a state board to reject the group’s application for a charter school.

“They are frankly running around at this point, trying to put together a financial package to make it work,” said Portland Mayor Michael Brennan, a critic of the proposed school, which he fears would siphon money from the city’s school system, as well as its top students.

Baxter Academy, which would be run by the nonprofit Baxter Academies of Maine, describes itself as a “rigorous, college-preparatory high school.”

The school would be in a building that housed a former call center on York Street. Its curriculum would focus on science, technology, engineering and mathematics. It has applications from 40 students, and hopes to have 160 students by September.

Baxter Academies of Maine is one of four groups that are vying for state charters under a year-old law that allows charter schools in Maine for the first time.

Maine is the 41st state to allow charter schools, which are public schools that don’t follow all of the regulations and restrictions on traditional public schools. If a public school student enrolls in a charter school, the state and local tax dollars from the student’s home school district follow the student to the charter school.

Careful analysis of any business plan is critical because a school that runs out of money would be very disruptive for students, said William Shuttleworth, vice chairman of the Maine Charter School Commission, which is reviewing Baxter Academy’s application.

When a charter school fails, he said, it’s usually because the first contract with the authorizing agency wasn’t well thought out, he said.

“My number one job, as commissioner, is to make sure we do the due diligence so every school we authorize is guaranteed for kids,” he said.

A national survey of charter schools during 2010-2011 showed that 6.2 percent closed when their charters came up for renewal and 1.5 percent closed during their charter terms, according to the National Association of Charter School Authorizers.

Friday is Maine’s deadline for groups to apply for charters. Six groups have applied.

The charter commission has already ruled that two of the applicants — both proposals for virtual schools — are not ready for the upcoming academic year and should re-apply next year.

On Friday, the commission will decide whether to give a charter to the Maine Academy of Natural Sciences, a magnet school that has operated since September on the campus of the Good Will-Hinckley Home for Boys in the central Maine town of Fairfield.

On Monday, the commission will decide whether to give a charter to Baxter Academy and the Cornville Regional Charter School, organized by parents who opposed the closure of Cornville’s elementary school two years ago.

The commission has yet to schedule a meeting on a proposal for the Fiddlehead School of Arts and Sciences at an existing preschool in Gray. In its first year, the school would be for children from preschool through first grade.

The Baxter proposal faces an additional financial hurdle because it’s the only proposal for which there is no existing school building.

In its initial application, Baxter proposed a $2.4 million budget to teach 160 students. Critics said the proposal was built on assumptions that seemed unlikely to materialize.

For example, the school said it anticipated $540,000 in grants — $360,000 in the first year — from the U.S. Department of Education.

But the average grant is $175,000 per year, and only 15 to 19 schools are awarded grants nationwide, said Rep. Chellie Pingree, D-Maine, who made inquires about the grant at Brennan’s request.

The discrepancy is the most obvious example of unrealistic assumptions in Baxter Academy’s financial plan, said John Kosinski, a lobbyist for the Maine Education Association, which supports the Good Will-Hinkley proposal but opposes Baxter Academy.

He said the plan in Portland is just too risky.

“Right now this budget is a house of cards,” he said. “If one thing doesn’t come through — if this grant doesn’t come through — the whole house collapses.”

John Jaques, who heads the nonprofit group behind Baxter Academy, said he is confident that the school will get the grant because it has a strong application, with letters of support from the Mitchell Institute, Gov. Paul LePage, U.S. Sen. Susan Collins, R-Maine, and Pingree.

To address criticism from the charter commission that its budget was too optimistic in its revenue and enrollment projections, Baxter Academies of Maine presented an alternative $1.1 million budget last week for an enrollment of 100 students. The new budget assumes a federal grant of $180,00 in the first year, half the amount projected in its initial budget.

The revised budget shows that the group plans to borrow $400,000 this summer for start-up costs, including $75,000 for academic software and computers, $30,000 for classroom furniture, and $94,000 for annual lease payments.

The first-year budget includes $261,000 in salaries and benefits for six teachers and an educational technician, and $225,000 for administrators.

No money is budgeted for transportation or food service.

By the end of the 2012-13 school year, the school will have received revenue to pay back the $400,000 and have $40,000 left over, said Jaques.

He said the loan, through SunTrust Bank, would be guaranteed by the chief executive officer of an international engineering company.

Jaques said the donor has asked to remain anonymous because he does not want to attract more requests for financial help. He said the donor is a supporter of charter schools nationwide that have science and math curriculums.

Jaques said the school’s critics want to protect the status quo, which is not working for many students, and are making up accusations to prevent the school from opening.

“This is school reform that needs to happen,” he said, “and it is virtually impossible to accomplish in a public school setting.”

Karen Malone of North Yarmouth wants to send her 16-year-old son to the school because it can offer him an individualized education plan with a wide range of technology courses. She said she and other parents are committed to helping the school succeed, by doing things such as fundraising and volunteering their time.

“We would do whatever we had to to make sure that the school would work,” she said. “These kids need the opportunity, and we can’t let them down.”

Staff Writer Tom Bell can be contacted at 791-6369 or at:

tbell@pressherald.com