With negotiations over a new collective bargaining agreement progressing slowly, MLB has asked for the assistance of a federal mediator to help resolve the ongoing lockout, according to industry sources.

Under the request, which was first reported by ESPN's Jeff Passan, the Federal Mediation and Conciliation Service would attempt to find common ground between players and owners if both sides agreed to the process, which is voluntary.

While mediation could theoretically bring the sides closer on a number of core issues, mediation offers no guarantee of a resolution.