A trickle of refugees have been allowed to cross the border from Greece into Macedonia - the first for two days following clashes earlier this week.
Macedonia briefly opened the border crossing overnight, letting around 170 people cross, Greek Police said.
However some 10,000 people remain camped at the crossing, awaiting their turn.
It comes after clashes broke out on Monday as hundreds attempted to storm the border crossing.
The rapid build-up of migrants stuck at Greece's northern borders risks leading to a humanitarian disaster, the United Nations High Commissioner for Refugees has warned.
"Europe is on the cusp of a largely self-induced humanitarian crisis", the UN refugee agency warned in a statement.
It urged better planning and accommodation for all those stuck in Greece.
The UNHCR also urged all EU member states to reinforce their capacity to register and process asylum seekers through their national procedures, as well as through the European relocation scheme.
The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.