LONDON — Prime Minister Theresa May is making her first overseas trip as Britain’s leader on Wednesday to meet German Chancellor Angela Merkel, a key figure in negotiating Britain’s exit from the European Union.

A week ago May replaced David Cameron, who resigned in the wake of Britain’s decision to leave the 28-nation bloc.

May’s office says the trip, which also includes a visit to French President Francois Hollande, will help forge “the personal relations that will pave the way for open and frank discussions in the months ahead.”

May is likely to be asked when she will invoke Article 50 of the EU’s constitution, which triggers a two-year process of quitting the bloc. She has said she does not plan to do that before the end of the year, but EU leaders say there can’t be any substantive talks about future relations until Britain does that.

May said Wednesday that while she doesn’t underestimate the challenge of negotiating the British exit, she firmly believes “that being able to talk frankly and openly about the issues we face will be an important part of a successful negotiation.”

The thorniest issue is likely to be the trade-off between access to Europe’s single market — which the British economy relies on — and control of immigration. EU leaders are unlikely to give Britain full access to the market unless it accepts the EU principle of free movement of people among member states.

Facing her first weekly prime minister’s question session in the House of Commons Wednesday, May did not answer directly when asked if Britain would be willing to leave the single market in order to guarantee migration controls.

She said the referendum result made clear that “people want control of free movement from the European Union.” But, she said, “we must also negotiate the right deal and the best deal on trade in goods and services for the British people.”

May has also announced that Britain is relinquishing its turn at holding the EU presidency in the second half of 2017.