Western nations and Russia locked horns Friday at the UN Security Council over renewing a mandate to deliver cross-border aid to 4 million Syrians, just hours before the provision was set to expire.
Voting was expected to take place on Friday afternoon in the New York headquarters of the world body, with two rival proposals in play.
Diplomatic sources said final discussions indicated that Germany and Belgium, which had been pushing for three crossing points to be kept open for a year, appeared likely to bow to Russian demands to maintain only two crossings and for a period of just six months.
The plan for three crossings, two from Turkey, one from Iraq, to stay open for a year was shot down in a December meeting by Russia and China, who used their veto power as permanent members of the 15-nation Security Council.
Russia, a key backer of the Syrian regime of President Bashar al-Assad, instead tabled its own proposal with only two entry points on the Turkish border and with an extension of just six months. But that proposal failed to get the minimum nine votes at the time.
US Secretary of State Mike Pompeo described the Russian and Chinese veto as "shameful" and told Moscow and Beijing "you have blood on your hands."
Washington's negotiating position had been less than subtle however, one diplomat told AFP, starting out with a demand for five crossing points that could be bargained down to its desired number of three.
The US also wrongly assessed that Moscow would not resort to a veto, which it did, the same source said.
The mandate has been in place since 2014, and has until now included four points of entry for foreign aid into Syria, two from Turkey, one from Iraq and one from Jordan, although the latter has long fallen into disuse.
The UN Office for the Coordination of Humanitarian Affairs said Friday four million Syrians are being supported by cross-border operations, 2.7 million of them in the northwest and another 1.3 million in the northeast.
As part of the negotiation process, on Thursday Germany and Belgium, offered a compromise to Russia, which insists that no measures should be implemented without Assad's agreement.
They suggested a six-month extension, until July 10, but with three points of entry. But Russia re-issued its own proposal stating that it wanted two crossing points and an extension of six months.
One western diplomat said Russia wanted to force recognition that Damascus had largely retaken control of territory inside Syria a year ago, admitting that Moscow was in a "strong position" in the face-off.
Russia sees the international authorization of cross-border aid shipments as "breach of sovereignty, and that is a reality," the western diplomat said.
Diplomatic sources told AFP Germany and Belgium were reconsidering their proposal to include just two crossing points being mandated for six months as a means of salvaging the mechanism, even if that meant a drastic reduction in their demands.
Otherwise, they feared the mandate could simply expire, something the Europeans might then be blamed for.
Amnesty International said in a statement Friday that the aid shipments were vital to people living in the northern region of Idlib, close to the Turkish border, which has been subjected to renewed fighting and bombardments recently.
"Cross-border delivery of humanitarian aid has offered a lifeline for millions of civilians in northern Syria, who for years have suffered as a result of severely limited access to basic services such as clean water and vital health care," said Lynn Maalouf, Amnesty's Middle East research director.