GENEVA — U.S. Secretary of State John Kerry on Monday said “several proposals” aimed at finding a way to restore at least a partial truce in Syria are being discussed, amid continuing attacks in the city of Aleppo.

Kerry met with Saudi Foreign Minister Adel al-Jubeir and with the U.N. envoy for Syria, Staffan de Mistura. He said progress was being made toward an understanding on how to reduce the violence in Aleppo but that more work was needed.

“There are several proposals that are now going back to key players to sign off,” Kerry said after meeting de Mistura. We are hopeful but we are not there yet… we are going to work very hard in the next 24 hours, 48 hours to get there.”

He did not say what the proposals were, adding that he would telephone Russia’s Foreign Minister Sergei Lavrov later Monday and that de Mistura was headed to Moscow on Tuesday for talks.

He said the United States and Russia have agreed that there will be additional personnel stationed in Geneva around the clock to make sure there is more accountability and a better ability to enforce the cessation of hostilities on a day-to-day basis.

For Aleppo, the U.S. is considering drawing up with the Russians a detailed map that would lay out “safe zones.” Civilians and members of moderate opposition groups covered by the truce could find shelter from persistent attacks by Assad’s military, which claims to be targeting terrorists.