U.K. Prime Minister Theresa May faces a fresh challenge on Monday to her attempt to formally start Brexit negotiations by the end of March, as lawmakers begin a line-by-line debate over legislation that would allow her to do so. The draft law passed its first hurdle on Wednesday when the lower chamber, the House of Commons, voted it through to the next stage, with just one dissenting lawmaker from May’s Conservative Party — former Chancellor of the Exchequer Ken Clarke.