Okla. Stat. tit. 26, § 26-5-130: Burden of proof on petitioner

The burden of proof shall be upon the petitioner to sustain the

allegations in his petition. However, failure of the contestee to

appear or answer thereto shall be deemed to place him in default,

and shall constitute an admission of the allegations of the

petition, in which event, if the board determines that the factual

allegations of the petition constitute appropriate grounds for

disqualification, such contestee's candidacy shall be stricken.