A high-powered EU delegation has landed in Scotland nervously anticipating a breakthrough in talks with donald trump at a crunch meeting on Sunday to avoid an escalating trade war with Washington.

The EU trade commissioner, Maroš Šefčovič, and a team of aides arrived at Glasgow Prestwick airport on Sunday morning to join an advance party led by the European Commission president, Ursula von der Leyen, who flew in on Saturday to prepare for one of the most critical meetings in her tenure, due to be held at 4.30pm.

With the US commerce secretary, Howard Lutnick, and the trade representative, Jamieson Greer, also flying in for the meeting at trump’s Turnberry golf resort, hopes are rising for a deal.

However, Trump is keeping the EU anxiously waiting, shouting on Sunday morning to Sky News television cameras stationed next to the golf course that the chances of a deal remained “50/50”.

Heading into a cool summer’s day in south-west Scotland, nobody on either side had been willing to consider that Trump would sign on the dotted line, even if he called von der Leyen “a highly respected leader”.

The president focused on playing golf at his coastal resort on Saturday and Sunday, abandoning a scheduled talk with the press travelling with him on his four-day visit.

Trump had torn up the first deal his team had sealed with Šefčovič two weeks ago, instead pushing to threaten 30% tariffs on all imports from the EU from 1 August – his self-imposed deadline for a deal.

On Friday Trump gave a “good 50-50” chance for a framework trade pact to be reached, adding that Brussels wanted to “make a deal very badly”.

Such an agreement would be the biggest reached yet by his administration, surpassing a $550bn (£409bn) accord with Japan last week and the UK trade deal secured in May.

The talks in Scotland will be closely scrutinised by jittery global investors before financial markets open on Monday morning, amid hopes for a deal to help limit the damage on the world economy.

After going to such extensive lengths – flying in top officials to what was a hastily arranged meeting during the US president’s holiday to Scotland – not reaching an agreement would risk going down as a failure of statecraft.

A deal would be the closing chapter on 200 hours of face-to-face negotiations and video calls that started with a meeting in the Roosevelt room in the White House between Šefčovič, Lutnick, the US Treasury secretary, Scott Bessent, and Kevin Hassett, one of Trump’s longest-serving economic aides.

While Šefčovič has been in almost daily contact with US counterparts since April, it is understood that Trump has taken a deep personal interest in the EU talks, demanding detailed briefings before his Scotland visit because he wants to close the deal himself.

However, nervousness prevails on the EU side over Trump’s unpredictability, especially after he said on Friday there were still about 20 sticking points, without detailing what they were.

If sealed, the deal would be seen as a victory for Trump nonetheless and show that his threats to impose tariffs on more than 60 countries has succeeded in extracted more revenue from third countries.

On Friday the US president described a deal with the EU as “the big one”, with €1.4tn (£1.22tn) at stake in annual trade ; involving Volkswagen cars, Cognac and Kerrygold butter sold to the US, and Boeing 747s, bourbon whiskey and liquified natural gas to the EU.

An outline agreement in principle centres on a baseline tariff of 15% on EU goods sold to the US, which is five percentage points more than the UK’s deal and triple the 4.8% average rate applied before Trump was elected.

However, EU diplomats concede that the previous world order was blown up on 2 April when Trump announced his “liberation day” plan, which included threatening the EU with 20% import duties.

A deal, even at 15%, would be seen as the painful price to restore stability for investors in the EU and manufacturers in key sectors such as the German, French and Swedish car industries, which, since April, have faced a 25% US tariff.