A Russian bid to halve access for humanitarian aid deliveries to Syria from Turkey failed at the UN Security Council on Wednesday, gathering only four of 15 votes.
Russia and China cast vetoes on Tuesday to block the council from extending its approval for a year of aid deliveries to Syria from Turkey through two border crossings.
Russia then put forward its own text that would only approve one of those crossings for six months.
The US ambassador to the UN, Kelly Craft, told Reuters she had urged her Security Council colleagues, who all voted in favour of Tuesday's resolution, to oppose Russia's, describing the choice as "good versus evil".
"We're talking about the difference between life and death for millions of Syrians," Ms Craft said.
She said that council members should continue to push to keep the two crossings open.
Russia and China have said cross-border aid deliveries are not needed because those areas can be accessed from within Syria.
The more than six-year cross-border aid operation is authorised until Friday.
Diplomats said another council member is likely to put forward a proposal to authorise the two Turkish crossings for six months.
A resolution needs nine votes in favour and no vetoes by Russia, China, the US, France or Britain.
During the coronavirus pandemic the council has been operating online, which means members have 24 hours to cast a vote on a draft resolution.
Seven council members voted against the Russian draft on Wednesday, while four abstained.
Ms Craft accused Russia and China of wanting to end all cross-border aid for Syria to help "prop-up" Syrian President Bashar Al Assad's government.
A crackdown by the Syrian regime on protesters in 2011 led to civil war, with Moscow backing Mr Al Assad and Washington supporting the opposition.
Millions of people have fled Syria and millions more are internally displaced.