United Teachers Los Angeles made the first required legal step toward a possible teacher strike by declaring an “impasse” on negotiations with the district’s teachers union, the Los Angeles Daily News reports.

The threat of a strike follows seven months of disagreement over contract negotiations between leaders of the district’s teachers union and UTLA administrators. The teachers union is demanding more than $800 million dollars to cover the cost of an 8.5 percent salary hike, among other stipulations.

The “impasse” declaration could allow a mediator to oversee future discussions if the California’s Public Employment Relations Board agrees with the declaration. The mediator would begin a month long legal process with a number of required steps, resulting in either an agreement or a strike, according to The LA School Report.