"These deadlines are firm and must be met in order for the city and my administration to move forward in our efforts to support legislation for additional funding," the mayor wrote. "This is a serious matter and I know you realize the gravity of my concerns."
The district has asked for $75 million to $110 million from the city to help close a $629 million budget gap. Nutter said he would seek the money to preserve a list of endangered priorities, including full-day kindergarten.
On Friday, School Superintendent Arlene C. Ackerman announced that she had found a way to save full-day kindergarten by using federal Title I money.
The administration was angered because Nutter learned of the deal only an hour before Ackerman announced it. Nutter also noted that shifting Title I aid simply created another hole elsewhere in the budget.
The mayor faces a difficult week of negotiations to persuade City Council to pass either a soda tax, which he would prefer, or a real estate tax hike. The soda tax would raise $80 million a year for the schools; a 10 percent property tax hike would generate about $95 million.
A Council committee hearing on the two proposals has been scheduled for Friday. With Council's summer recess set for June 16, action likely must be taken this week if Nutter is to win more money for the schools.
Nutter's letter appears to address some of the objections Council members have raised to writing such a big check for the schools - primarily that the state-controlled district has done a poor job of budgeting and does not have to answer to the city for the way it spends money.
Most Council members have expressed at least initial opposition to raising taxes but have acknowledged that something must be done to help the schools.
A spokesman for the district did not return a phone call Sunday night.
Included in the mayor's letter was a chart that lays out seven potential scenarios for more city money and restored state funding, coupled with SEPTA paying for student TransPasses.
The amounts vary from a low of $54 million to a high of $206 million. Under each scenario, the district is being asked to say exactly how the money would be spent in order of priority.
"Now is the time for rapid response and a clearing of the air," the mayor wrote. "We need facts and clear statements about what the district will do with any restoration of funds."
The mayor is calling for much greater city oversight of the schools, and he's asking that the superintendent be required to submit an annual five-year plan to the reform commission and city.
That would be similar to the city's budget process, which requires a five-year plan to be submitted to a state oversight agency.
State Education Secretary Ronald Tomalis said Sunday night he had been in discussions with the Mayor's Office about the district budget crisis. The state provides about half the district's funding, and the city contributes about 30 percent.
"I think many of the questions the mayor is asking are very valid questions," Tomalis said. "We've been asking many of the same things . . . not just about the use of state dollars, but federal dollars."
Contact staff writer Troy Graham at 215-854-2730, firstname.lastname@example.org, or @troyjgraham on Twitter.