29 CFR §101.22

1. (a)The investigation of an alleged violation of section 8(b)(7) of the Act is initiated by the filing of a charge. The manner of filing such charge and the contents thereof are the same as described in § 101.2. In some cases, at the time of the investigation of the charge, there may be pending a representation petition involving the employees of the employer named in the charge. In those cases, the results of the investigation of the charge will determine the cause of the petition.
2. (b)The investigation of the charge is conducted in accordance with the provisions of § 101.4, insofar as they are applicable. If the investigation reveals that there is merit in the charge, a complaint is issued as described in § 101.8, and an application is made for an injunction under section 10(1) of the Act, as described in § 101.37. If the investigation reveals that there is no merit in the charge, the Regional Director, absent a withdrawal of the charge, dismisses it, subject to appeal to the General Counsel. However, if the investigation reveals that issuance of a complaint may be warranted but for the pendency of a representation petition involving the employees of the employer named in the charge, action on the charge is suspended pending the investigation of the petition as provided in § 101.23.