Four days before the contract of thousands of Philadelphia public- school teachers was set to expire, the teachers union and the school district have agreed to a 60-day extension.

In a joint statement released yesterday, both sides agreed that the extension would permit the district and the Philadelphia Federation of Teachers "to fully focus on a successful and smooth opening of the 2009-2010 school year."

A district spokeswoman said that both sides are committed to reaching an agreement.

"The issues on the table are challenging, but we're still talking, and no one has walked away from the table," said spokeswoman Evelyn Sample-Oates.

Since negotiations began, however, disputes over key issues have slowed progress between a historically powerful union and an administration set to uproot tradition with controversial proposals.

Superintendent Arlene Ackerman has pushed for longer school days, merit-based pay based on student performance and the end of seniority-based teacher assignments. Union officials have bemoaned what they said is the district's plan to diminish teachers' control.

District and union leaders agreed that the extension will help lift pressure off everyone involved.

The union and district agreed last August to a one-year contract extension, and the new dealine for a contract is Oct. 31.

But PFT President Jerry Jordan said that most of the district's 16,000 teachers are just hoping for an end to the issue.

"Teachers would like to have this resolved so that [they] can return to work and focus on opening school," he said.

The first day of school is Sept. 8.

Jordan noted that the state budget stalemate had also factored heavily in the mutual decision. Sixty percent of the district's budget relies on state support, which is in limbo as legislators deal with a $3.2 billion deficit.

The district hopes to get $1.65 billion from the state to pay for improvements, including smaller class sizes, librarians and nurses in every school, art and music programs in the district's 177 elementary schools and increased assistance and development programs for new teachers.