The United Kingdom will ultimately leave the European Union on the terms of Prime Minister Boris Johnson's deal, a senior Downing Street source said on Thursday, as EU leaders mulled offering London a three-month flexible Brexit delay. More than three years after voting 52%-48% to be the first sovereign country to leave the European project, the United Kingdom is waiting for the EU to decide how long the latest delay to Brexit should be. "This ends with us leaving with the PM's deal," a Downing Street source who spoke on condition of anonymity said. "We will leave with a deal, with the PM's deal." When asked when Brexit would happen, given that the current deadline of Oct. 31 is only a week away, the source said: "Parliament has taken back control." Johnson won the top job by staking his career on getting Brexit done by Oct. 31, though he is almost certain to fail to do that after parliament defeated his proposed legislative timetable on Tuesday. So will there be an election before Christmas? "Perhaps," the Downing Street source said. "We shall see." As British politicians discuss the pros and cons of a Christmas election, responsibility for the timing of Brexit has passed to other European capitals: Berlin supports a three-month delay, while Paris is pushing for a shorter one. Timing is crucial to the Brexit riddle. While both German Chancellor Angela Merkel and French President Emmanuel Macron appear to be fatigued by Brexit, they fear a no-deal exit that would almost certainly hurt global growth, roil financial markets and create a potentially deeper EU crisis. To offer Britain a long extension would take the pressure off British lawmakers to approve Johnson's deal and open up possibilities such as a referendum on it. A short extension might focus minds in the British parliament.