Gaps in Gaza ceasefire talks under way in Qatar between Israel and Palestinian militant group Hamas can be bridged but it may take more than a few days to reach a deal, Israeli officials said on Tuesday.

Israel and Hamas are believed to have agreed that 10 living hostages and the remains of 18 others should be released during the first 60 days of a cease-fire, but they have not reached a consensus on how many Palestinian prisoners should be freed during the same period. Up to 20 hostages are still thought to be alive.

President Donald Trump’s foreign envoy Steve Witkoff said Tuesday that he’s hopeful to have a Gaza ceasefire deal by the end of the week, as negotiators make substantial progress working through remaining issues.