U.S. President Donald Trump is in Sicily on May 26 for a two-day Group of Seven (G7) summit at which he is expected to face questions from other leaders about his positions on trade and climate change.
The G7 meeting in the resort town of Taormina is the last leg of Trump's first foreign trip since taking office in January -- a nine-day tour of the Middle East and Europe.
The leaders are also due to discuss security cooperation following the May 22 bombing at a concert in Manchester that killed 22 people and was allegedly carried out by a young Islamist militant of Libyan descent who grew up in Britain.
An unnamed senior Italian diplomat said Trump and the heads of Britain, Germany, France, Italy, Japan and Canada had similar views on many issues ahead of the two-day summit, but Washington remained isolated on commerce and the environment.
European Union states want a clear U.S. pledge "to fight all forms of protectionism," said the diplomat. But they were struggling to convince the U.S. president of the merits of free trade.
"We will have a very robust discussion on trade and we will be talking about what free and open means," White House economic adviser Gary Cohn told reporters late May 26.
He also predicted "fairly robust" talks on whether Trump should honour a U.S. commitment to cut greenhouse gas emissions under the 2015 Paris Agreement.
He said the president, who has dismissed global warming as a "hoax," would make a final decision when he returned home, but stressed that he would put economic development first.
European diplomats expect their leaders to put pressure on Trump about the Paris emissions deal, which has comprehensive support across the continent.
After visits to Saudi Arabia, Israel and the Palestinian Territories, Trump met Pope Francis in Rome on May 24 and held talks May 25 with the heads of the European Union and the NATO military alliance in Brussels.