Kerry has pointedly avoided new bilateral negotiations with Lavrov, and his invitation to the Turkish, Saudi, Qatari and Iranian foreign ministers to join them for talks in the Swiss lakeside town of Lausanne will broaden the discussion to include the most powerful backers of Syria's government and rebels.
"I don't know that I would expect any breakthroughs. I would just say that we're working to get this multilateral effort and approach to Syria up and running," US State Department spokesman Mark Toner told reporters in Washington.
Pressure is rising for a halt to a ferocious, three-week-old Syrian government offensive to capture the rebel-held eastern zone of the city of Aleppo, where the United Nations says 275,000 civilians still live and 8,000 rebels are holding out against Syrian, Russian and Iranian-backed forces.
Western powers have accused Russia and Syria of committing atrocities by bombing hospitals, killing civilians and preventing medical evacuations, as well as targeting an aid convoy with the loss of around 20 lives.
Syria and Russia counter that they only targeting militants in Aleppo and accuse the United States of breaking the ceasefire by bombing scores of Syrian troops fighting Islamic State insurgents, over which the United States has expressed "regret".
A senior rebel commander said on November 14 Syrian government forces would never be able to capture Aleppo's eastern sector, but a military source said the operation was going as planned.
The United Nations has said food, fuel and medicine are running out in eastern Aleppo and there will be no rations to distribute from the start of next month.
In a gesture of apparent desperation, UN Syria peace envoy Staffan de Mistura has offered to escort members of an Islamist militant group, Jabhat Fateh al-Sham, out of Aleppo if that would entice Damascus to forge a ceasefire with the remaining rebels.
Lavrov has said he does not plan to bring any new ideas to Lausanne. But his deputy Gennady Gatilov said Russia wants to discuss de Mistura's offer, as well as elements of last month's failed truce deal, namely humanitarian aid deliveries and a pullout of both sides' troops from the Castello Road, a key supply route.
"And it's about time to start moving toward an inclusive political process," Gatilov told Interfax news agency.
Many in Syria's opposition say Kerry has put too much trust in Lavrov, with protracted diplomatic wrangling over ceasefires buying time for Russia's military campaign and obscuring the once central question of the fate of President Bashar al-Assad, while the clock runs down to the US elections on Nov. 8.