LONDON—President Trump and European Commission President Ursula von der Leyen are scheduled to meet Sunday during the U.S. president’s visit to Scotland, raising hopes that the U.S. and Europe are close to a trade deal that would avoid a trans-Atlantic trade war.

U.S. President Donald Trump on Friday said there was a 50-50 chance that the United States would reach a trade agreement with the European Union. Trump spoke to reporters as he left the White House to head to Scotland for several days of golfing and bilateral meetings.

President Trump has threatened to impose a 30% tariff on imports from the European Union's 27 member countries if no trade deal is reached by Aug. 1.