Mo. Rev. Stat. § 115.563: Contests for office of senator or representative to be heard by respective body.

1. All contested elections for the office of state senator shall be heard and determined by the state senate. All contested elections for the office of state representative shall be heard and determined by the state house of representatives.

2. Any contest based on the qualifications of a candidate for the office of state senator or state representative which have not been adjudicated prior to the general election shall be determined by the state senate or the state house of representatives, as the case may be.