By Sinead Carew NEW YORK (Reuters) – The S&P closed at a record high and the Dow Jones Industrial Average broke above the 24,000 mark for the first time on Thursday as investors gained confidence that the Republican party’s push for a U.S. tax overhaul would succeed. Republican Senator John McCain’s decision to back the tax bill provided a new jolt of momentum for the legislation. McCain had helped defeat Republicans’ efforts to repeal Obamacare, and a “yes” vote by him on the tax measure was considered crucial.
