Being the first European leader through the door of Donald Trump's White House is an honor that Theresa May worked hard to get. But it's one that comes with a daunting set of challenges.

The British prime minister will visit Washington on Jan. 27, seven days after Trump took office. Her stated goal is to engage the new president on questions about the future of the North Atlantic Treaty Organization and Syria's civil war. Her most important task is to nail down details of what a U.S.-U.K. trade deal would cover.

But what common ground can there be between a prime minister who sees herself as a champion of global free trade and a president who sees commerce as "other countries making our products, stealing our companies and destroying our jobs"? How does a woman with a Muslim in her Cabinet deal with a man who said he wanted to ban all adherents of Islam from entering the U.S.? Speaking on Sunday, May was keen the emphasize the positive.