JEFFERSON CITY, Mo. — Legislation that would impose new requirements for expert testimony in Missouri court cases has run into opposition from two Republican senators who are lawyers and running for statewide office. Republican Sens. Eric Schmitt, of Glendale, and Kurt Schaefer, of Columbia, have helped Democrats stall the measure, which is backed by business groups. Both said it could cost businesses more in litigation fees because of the higher standard and likely prolonged legal challenges to expert …