TOPEKA, Kan. (AP) - A legal dispute over the lack of a Democratic candidate for the U.S. Senate in Kansas could upend a key contest in the fight for control of the Senate. The national spotlight is on three-term Republican Senator Pat Roberts and independent challenger Greg Orman. But a case being heard Monday by a three-judge panel in Shawnee County District Court centers on whether state law requires Democrats to pick a new candidate after Chad Taylor withdrew earlier this month. Kansas Secretary of State Kris Kobach has asked the court to render a decision by October 1. But regardless of the court's decision, the losing side is expected to appeal the case. University of Kansas Law Lecturer Mark Johnson says that would further delay the printing of ballots for the November election. "We're going to end up with a lot of ballots that are defective and will have to be excluded and that may well be a violation of federal law." Johnson says a federal violation would likely trigger a Justice Department lawsuit against the state.