Secretary of State Marco Rubio expressed optimism Sunday that a deal between Hamas and Israel to end the war in Gaza could finally be reached, saying it is “the closest we’ve come to getting all of the hostages released.”

But the top U.S. diplomat also cautioned that nothing is a done deal, saying there are key components of the peace plan put forth by President Donald Trump that still need to be worked out, caveating, “there’s a lot of pitfalls along the way.”

“This is the closest we’ve come to getting all of the hostages released, every single one, all 48 including the 28 who are deceased,” Rubio told ABC News’ “This Week” co-anchor Martha Raddatz. “But there’s a lot of pitfalls along the way. There’s some work to be done here.”

Rubio said that “some of the technical talk” was already ongoing, and stressed that the U.S. believes speed is paramount, especially for what he described as the first phase of this deal: returning the hostages to Israel.

“[President Trump] wants to see it happen quickly. This is not something that can drag out. We cannot be here three weeks from now, still discussing, you know, the logistics of how hostages are going to be released. That has to happen very quickly in order for the rest of this deal to gain momentum,” Rubio said.

He continued, “Our hope is that by the time our team gets to Cairo, 90% of this has been worked out, and we’re just sort of finalizing the logistical piece. We’d like to see it done yesterday.”

Mediators are set to begin further negotiations between Israel and Hamas on Monday in Egypt, the country’s foreign ministry said. U.S. special envoy Steve Witkoff and Jared Kushner, Trump’s son-in-law, will be part of the U.S. team participating in the talks.

This is a developing story. Please check back for updates.