The two rivals to become the U.K.'s next prime minister stepped up their campaigns, with Energy Minister Andrea Leadsom extolling the virtues of motherhood while Home Secretary Theresa May, who is childless, pledged to get Britain through the "difficult times" that Brexit will bring.

Prime Minister David Cameron's successor will be chosen by the Conservative Party's 150,000 members. May, who quietly backed the campaign to remain in the EU, has the support of most of her fellow lawmakers, while Leadsom is touting her "Leave" credentials to drum up votes among a predominantly Euroskeptic base.

May committed to withdrawing Britain from the 28-nation bloc and said that "control of free movement" will be part of that. "But alongside that, it's important to show how we can come through what will be, I think, some difficult times with a better, brighter future," the Telegraph newspaper quoted her as saying in an interview.