In an effort to avert a potential national rail strike, U.S. Labor Secretary Marty Walsh was part of a Sept. 7 session at the National Mediation Board involving the organization representing railroads in national contract negotiations, as well as eight unions that have not yet reached tentative contract agreements, Politico reports.

Negotiators from the two sides are slated to again meet with the Mediation Board Sept. 8 and Sept. 9, in an effort to avert a strike or lockout on Sept. 16, when the current 30-day cooling off period ends. That period for negotiation began when the Presidential Emergency Board appointed by President Joe Biden issued its recommendations for settling the long-running contract dispute in August.

Read more: Industry Organizations Vulnerable to Rail Strike Applaud Biden’s Creation of Emergency Board

Five unions have announced tentative agreements based on the PEB recommendations, most recently the International Brotherhood of Electrical Workers and American Train Dispatchers Association. The Politico report says other unions have reached agreements that have not been announced, citing “a person familiar with the conversations,” but that unions representing engineers and conductors still see major issues and railroads are not budging.