(Salem,OR) -- Two Oregon State Senators are challenging the Oregon Secretary of State's decision to disqualify them from next year's election. The Secretary of State says ten senators with more than ten unexcused absences can't run for reelection, because they would violate the voter approved Ballot Measure 113. Six of those seats are open next year. Thursday was the first day candidates could file for the May Primary. Senate Republican Leader Tim Knopp of Bend and Klamath Falls Senator Dennis Linthicum filed for reelection. A group of lawmakers is suing, saying the measure's language is unclear. Linthicum's wife Diane has also filed for the Klamath Falls senate seat.