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.

As European Commission President Ursula von der Leyen is set to meet with President Donald Trump this weekend to discuss trade, Trump himself may be the biggest hurdle standing in the way of a deal.

President Donald Trump put the odds of striking a trade deal with Europe to reduce the tariff rate on their imports at 50-50, even as diplomats from the trading bloc have expressed optimism in recent days that an agreement could be near.