Maryland Gov. Larry Hogan (Jabin Botsford/The Washington Post)

Maryland Gov. Larry Hogan may have exceeded his authority by ordering public school systems to start after Labor Day, according to the state attorney general’s office, whose opinion was sought by Democratic lawmakers opposed to the Republican governor’s action.

“I can not say unequivocally that the Labor Day executive order exceeds the Governor’s authority, but I believe it likely that a reviewing court, if presented with the issue, would conclude that it does,” Adam D. Snyder, a lawyer in the office of Attorney General Brian E. Frosh (D), wrote in a 24-page letter that was delivered Friday to state Sen. Paul G. Pinsky (D-Prince George’s County) and Del. Anne R. Kaiser (D-Montgomery).

Snyder also wrote that the General Assembly has the authority to pass legislation to override Hogan’s executive order.

The review from Frosh’s office seems certain to fuel the partisan battle that began more than two weeks ago, after Hogan ordered the state’s 24 school systems to start after Labor Day and to end by June 15 starting next year. Systems may petition the state Board of Education to be exempt from the order.

The governor said a post-Labor Day start would provide a boost to tourism-based businesses, give families more time together and keep students out of hot classrooms. Democratic lawmakers and many school officials said the order would limit flexibility in the school calendar, cut into learning and test-preparation time and add to the financial burden on families who are struggling economically and need to provide child care.

Snyder wrote that his letter was advice to Pinsky and Kaiser, not an official opinion from the attorney general’s office.

After reading it, Pinsky said he would advise the state’s school systems to ignore the governor’s executive order.

“They should set a calendar that is appropriate to them and their students,” he said. “The governor can choose to take 24 school systems to court, and he would have a weak case.”

He said he does not think that legislation is warranted but that he would be willing to participate or lead a legislative effort to overturn the order if necessary.

Doug Mayer, a spokesman for Hogan, scoffed at Snyder’s letter and sought to minimize its significance.

“Even by lawyer standards, taking 24 pages to reach a ‘I don’t know,’ is unprecedented,” Mayer said in an email. “The Attorney General’s office has a lot of political opinions, and we agree with almost none of them, including this halfhearted one.”

Since Hogan signed the order Aug. 31, school district administrators have complained that the mandate upends their calendars. As they have begun planning for next school year, many have warned that the change could lead to a shorter spring break.

Democratic lawmakers have been trying to figure out how to respond, arguing that the idea of extending summer break might be popular but is not good policy.

Their main complaint: Hogan pushed it through using an executive order instead of the legislative process.

“There might be a legitimate argument to this, but you don’t do it by executive order,” House Speaker Michael E. Busch (D-Anne Arundel) said after Hogan issued the order.

Kaiser said Hogan’s mandate infringes on local control. “I’ve heard from professionals up and down the line who have said that the governor’s executive order does nothing to help education, teachers, students and schools,” she said.

Hogan said he took the action because the General Assembly would not, noting that the measure has been proposed in the legislature before but never made it out of committee. A bipartisan task force appointed by Hogan’s predecessor, Democrat Martin O’Malley, also recommended a post-Labor Day start.

Hogan has blamed the teachers union for blocking the bill. But the legislation was also strongly opposed by the school boards association, state PTA and school superintendents.

Michael Meyerson, who teaches constitutional law at the University of Baltimore School of Law, said he would not be surprised if the Court of Appeals has the last word on the issue.

“School calendars are traditionally a county decision, and the legislature has always been the entity passing laws governing the length of the calendar,” Meyerson said. “This is a novel intrusion into the role of both the legislature and the counties.”