Application for such restraining order may be made by any candidate for such office and shall be made by petition duly verified under oath setting up the material facts relative to the election and the election contest involved. Such petition shall be heard in open court, and the court shall give such notice of the hearing on such application as it shall deem sufficient to the candidates for the office of United States senator in the election concerning which the application was filed and to such persons as shall be named in such application. Pending such hearing, any justice of the supreme court may, in his discretion, grant a temporary order restraining any interference with said ballot boxes or the ballots therein.