WASHINGTON (Reuters) - U.S. House Speaker Paul Ryan on Wednesday called on health insurance companies to “stick it out” in the Obamacare marketplace despite concerns over its stability, saying  Republicans are continuing their push to replace current law. Speaking in an interview with Axios news outlet, Ryan said he could not address ongoing litigation over the fate of the Obamacare cost-sharing subsidies but that he has encouraged insurers to still participate in 2018. 