Standard & Poor’s downgraded its long-term outlook for the University of Maine System from stable to negative on Tuesday, citing declining enrollment and high turnover among leadership at the seven campuses.

The New York credit agency left the system’s credit rating unchanged at AA- on outstanding revenue debt, and also assigned a rating of AA- to the system’s $46.24 million in 2015 bonds.

Downgrading the outlook means that S&P thinks the system’s rating could be downgraded to an A+ if declining enrollment and revenue continue. A lower credit rating would mean the system would have to pay higher interest rates on any future borrowing.

“The revised negative outlook and rating reflect our view that UMS is experiencing enrollment pressure,” Standard & Poor’s credit analyst Ken Rodgers said in a press release.

Enrollment was down 2.5 percent systemwide last fall. Overall, enrollment is down 7.5 percent over the last five years.

Rodgers also noted that four of the campuses have interim presidents, saying that the “significant turnover in leadership” means “we feel some weakness in governance and management might be occurring.”

Rodgers also noted Maine’s weak economy, a declining number of 17-year-olds and strong regional competition from other universities and colleges as factors in the negative outlook.

University system officials noted that the rating itself was unchanged.

“S&P has affirmed our AA- rating, reflecting the university system’s commitment to sound fiscal management,” spokesman Dan Demeritt said in an email.

“The agency’s decision to revise its long-term outlook is a realistic assessment of the demographic, fiscal and competitive challenges that led Chancellor (James) Page and the Board of Trustees to launch a change initiative that will administratively and academically align our seven institutions as one university,” he said.

In January, Page announced a plan to consolidate all administrative functions but maintain the seven-campus system.

Rebecca Wyke, the vice chancellor for finance and administration, said the S&P outlook was “reasonable” given the system’s financial pressures.

UMS faces a potential $90 million deficit by 2020, based on trends in the system’s current $529 million budget. Wyke told the trustees in November that the deficit could be cut to $59 million if tuition revenue and the state appropriation increase annually at the same rate as the consumer price index, and if the system can reduce health care costs, expected to rise 7 percent a year.

Wyke outlined four potential scenarios that would close the $59 million budget gap: increasing the state appropriation by 7.4 percent annually through 2020; increasing tuition by 5.5 percent annually; increasing enrollment by 4.2 percent annually; or reducing the workforce by 14.5 percent, or 685 full-time employees. For the past three years, tuition at University of Maine System schools has been frozen, as has state funding.

Gov. Paul LePage’s recent budget proposal would increase funding for UMS by 3.6 percent – half of what the system requested – over the two-year budget, to $182.6 million for the fiscal year ending in June 2017.

At the same time, university officials have instituted measures to cut costs in recent years. Retiring faculty members have not been replaced, annual layoffs have become the norm, and the system is undergoing a review to reduce redundancy and streamline course offerings.

S&P’s outlook “underscores exactly what we’re trying to do,” Wyke said. “It would be better if we were further along with the chancellor’s plans, but I think we are doing the right thing,”

The $46 million in 2015 bonds for UMS includes $22 million to refinance old debt at a lower interest rate, saving $3.5 million, and $13 million for two energy projects at the Machias and Farmington campuses, Wyke said.

The system does not have plans to seek any new financing in the next two years, she said.

S&P has been increasing the number of downgrades in the higher education sector in general.

Last month, the agency issued a report saying the outlook remained “negative” for the overall not-for-profit higher education market in 2015, citing rising costs for colleges and students.

The ratio of S&P downgrades to upgrades in higher education has risen for four years in a row, with 30 downgrades compared to seven upgrades in 2014, according to the report, “Upping The Ante: Costs Of Luring Top Students Keep The Outlook Negative On U.S. Not-For-Profit Higher Education Sector.”

By comparison, the outlook for the University of Chicago was downgraded to negative from stable, while Southern New Hampshire University’s outlook was upgraded from stable to positive.

S&P said 11 percent of its rated not-for-profit institutions have negative outlooks, 5 percent have positive outlooks, and the vast majority, 84 percent, have stable outlooks.

The negative schools include five Illinois public universities and some private colleges and universities in Pennsylvania and New York, while 19 of the 49 negative outlooks are private universities with a BBB rating, lower than the A- rating.