Theresa May set to replace Cameron as rival quits UK PM race

By Elizabeth Piper and Mark Trevelyan LONDON (Reuters) - Home Secretary Theresa May is set to become Britain's first woman prime minister since Margaret Thatcher after her only rival abruptly quit the race on Monday, removing the need for a drawn-out leadership contest. May, 59, was left as the only candidate to succeed David Cameron, who announced he was stepping down after Britons voted last month to leave the European Union. Britain's planned withdrawal has weakened the 28-nation bloc and cre