The St. Paul Public Schools and the union representing its teachers have agreed to seek a state mediator’s help in forging a deal on a new contract.

“State mediation has been a useful tool in each of the last three rounds of negotiations for the teacher contract in St. Paul,” the district said Friday in a news release.

Two previous moves to mediation had a distinctly harsher edge.

In 2013, district negotiators walked out of a bargaining session, and declared their intent to seek mediation, after representatives of the St. Paul Federation of Teachers turned down a request to work with the district on an alternative teacher pay plan.

Then, in 2015, the union pushed for mediation, and threatened to strike, over school safety concerns triggered in part by the beating of a Central High teacher.

By taking talks into mediation, district and union negotiators now will work in private. Their last public negotiating session was on Thursday night.

Minneapolis Public Schools requested mediation in November in its talks with the Minneapolis Federation of Teachers, saying it could expedite attempts to reach a deal.

The Minnesota Bureau of Mediation Services has agreed to assist in those negotiations, which are set to begin in January.