Before the meeting, expected at 1530 GMT Sunday (0130 AEST Monday) on Trump's golf course in Turnberry, western Scotland, US and EU teams were in final talks on tariffs for crucial sectors like cars, steel, aluminium or pharmaceuticals.
US Trade Representative Jamieson Greer and Commerce Secretary Howard Lutnick flew to Scotland on Saturday and EU Trade Commissioner Maros Sefcovic arrived on Sunday morning.
Lutnick told "Fox News Sunday" that the EU needed to open its markets for more US exports to convince Trump to reduce a threatened 30 per cent tariff rate that is due to kick in on August 1.
"The question is, do they offer President Trump a good enough deal that is worth it for him to step off of the 30 per cent tariffs that he set," Lutnick said, adding that the EU clearly wanted - and needed - to reach an agreement.
A separate U.S. administration official was upbeat that a deal was possible. "We're cautiously optimistic that there will be a deal reached," the official said, speaking on condition of anonymity. "But it's not over till it's over."
Ambassadors of EU governments, on a weekend trip to Greenland organised by the Danish presidency of the EU, held a teleconference with EU Commission officials on Sunday to agree on the amount of leeway von der Leyen would have in the talks.
In case there is no deal and the U.S. imposes 30 per cent tariffs from August 1, the EU has prepared counter-tariffs on 93 bn euros ($A164 bn) of US goods.
EU diplomats have said a deal would likely include a broad 15 per cent tariff on EU goods imported into the US, mirroring the U.S.-Japan trade deal, along with a 50 per cent tariff on European steel and aluminium for which there could be export quotas.
The EU deal would be a huge prize, given that the US and EU are each other's largest trading partners by far and account for a third of global trade.
EU officials are hopeful that a 15 per cent baseline tariff would also apply to cars, replacing the current 27.5 per cent auto tariff.
Some expect the 27-nation bloc may be able to secure exemptions from the 15 per cent baseline tariff for its aerospace industry and for spirits, though probably not for wine.
The EU could also pledge to buy more liquefied natural gas from the US, a long-standing offer, and boost investment in the United States.
The US president, in Scotland for a few days of golfing and bilateral meetings, told reporters upon his arrival on Friday evening that von der Leyen was a highly respected leader and he was looking forward to meeting with her.
