After days of speculation, the British government announced on Dec. 17 that the House of Commons will vote on Prime Minister Theresa May's Brexit agreement with the European Union during the week of Jan. 14. The vote had been set for Dec. 11, but May postponed it by a month to avoid defeat. The United Kingdom is set to leave the European Union on March 29. By putting off the vote for a month, May is hoping to raise the stakes and pressure on Commons to approve her deal. It's a risky strategy: May will still struggle to persuade enough members of Parliament to support her plan. A rejection by Commons in mid-January would give May's government only about 10 weeks to negotiate a new exit deal with the European Union or seek another vote in Parliament, which would significantly increase the chances of a disorderly Brexit. Several scenarios could...