The decision by Leadsom, who supported the Brexit "leave" campaign, is a defeat for the Euroskeptic wing of the Conservative Party. Two of the other candidates who applied to lead the party supported the "leave" camp but were eliminated in the first round of party voting. May, on the contrary, supported Britain's EU membership but kept a low profile during the campaign. When she first announced her candidacy for prime minister June 30, she said, "Brexit means Brexit," and ruled out a second referendum or early elections. During a press conference July 11, May insisted that there would be no second referendum, even if public mood changes.

Originally, the next Conservative leader was to have been announced by Sept. 9, but with no opponents to May's candidacy remaining, the timetable was advanced. The fast appointment of a new prime minister makes the United Kingdom's political situation clearer and prevents uncertainty that would have hurt the British economy. But the country's political problems are not over. May will lead a divided party and a divided country at a time when unity is needed. Some legal experts in the United Kingdom have said the prime minister needs formal authorization from Parliament to start withdrawal negotiations with the European Union, though other government lawyers contradict that view. Regardless, getting authorization will be anything but easy for the prime minister in the current social and political environment. The British government already dismissed a request on July 9 by a group that collected over 4 million signatures to demand a second referendum. Similarly, the opposition Labour and Liberal Democratic parties have demanded early elections, a scenario that May has ruled out.

May has been vague when it comes to formally notifying the European Union of Britain's intention to leave the bloc. London's formal notification would trigger a two-year negotiation period, during which time the terms of the divorce (and, ideally, the terms of the new bilateral relationship) have to be defined. May has suggested that the announcement be delayed a few months to enable the new government to come up with a coherent negotiation strategy. The European Union will probably give the new prime minister some time. Brussels will officially reject any informal negotiations before the formal announcement is made, but contacts between London and several EU capitals are likely to start as soon as the new prime minister takes office.

There will be multiple items on the bilateral agenda, but the free movement of EU citizens will be one of the most prominent. The United Kingdom is interested in preserving its access to the EU internal market because the bloc is its main trade partner. EU officials have said, however, that to retain its access to the internal market, the United Kingdom will have to accept EU workers. Switzerland and Norway, which are not EU members, offer a precedent for this: Both countries accept workers from EU member states in exchange for access to the common market.

But the free movement of EU workers was one of the most important issues during the referendum campaign in Britain. The "leave" camp campaigned on the promise to stop the arrival of EU workers, and polls suggest that immigration is an important issue for people who voted to leave. On July 11, May said that stopping the free movement of EU workers takes priority over retaining access to the single market. Thus domestic needs will shape the upcoming negotiation between the United Kingdom and its EU peers.