Secretary of State Antony Blinken arrived in Israel on Sunday evening local time ahead of cease-fire talks that are scheduled to resume in Egypt this week.

Following discussions in Doha, Qatar, last week, senior officials are due to meet again this week in Egypt. Israel has said it will send a team to Cairo to continue talks, but Hamas has dismissed any hint of progress as an "illusion."

While in Israel, Blinken is scheduled to meet with Israeli Prime Minister Benjamin Netanyahu and other senior officials to press for a cease-fire agreement. Netanyahu has expressed "cautious optimism" about the talks, but said Sunday that "there are things we can't be flexible about."

-ABC News' Joe Simonetti

Israeli Prime Minister Benjamin Netanyahu said Sunday that Israel "can’t be flexible” about certain things while cease-fire talks continue.

Netanyahu commented on the cease-fire talks during his weekly cabinet meeting and ahead of Secretary of State Antony Blinken's scheduled arrival in Israel on Sunday evening local time.

"We are conducting very complex negotiations when on the other side is a murderous, uninhibited and recalcitrant terrorist organization," Netanyahu said, referring to Hamas. "But I want to emphasize -- we are conducting negotiations, not negotiation. There are things we can be flexible about, and there are things we can't be flexible about -- and we insist on them. We know very well how to differentiate between the two."

Following discussions in Doha, Qatar, this week, senior officials are due to meet again next week in Egypt. Israel has said it will send a team to Cairo to continue talks, but Hamas has dismissed any hint of progress as an illusion.

"Therefore, besides the great efforts we are making to return our abductees, we stand firm on the principles we have established, which are essential for Israel's security. These principles -- I repeat -- are consistent with the May 27 outline, which received American support," Netanyahu said Sunday.

Netanyahu said Hamas has refused to negotiate, noting it did not send a representative to the talks in Doha.

"Therefore, the pressure should be directed at Hamas and Sinwar, and not at the Israeli government," he said, referring to Yahya Sinwar, the newly named political leader of Hamas and one of the key architects of Hamas' Oct. 7 surprise attack on Israel. "The strong military pressure, and the strong political pressure, this is the way to achieve the release of our abductees."

-ABC News' Jordana Miller

Secretary of State Antony Blinken will land in Tel Aviv, Israel, on Sunday evening as talks over a Gaza cease-fire hang in the balance.

Following discussions in Doha, Qatar, this week, senior officials are due to meet again next week in Egypt. Israel has said it will send a team to Cairo to continue talks, but Hamas has dismissed any hint of progress as an illusion.

Vedant Patel, the State Department’s principal deputy spokesperson, told reporters at a Thursday briefing that the parties are yet to settle "some specific details, some specific implementing factors," but that there is "broad agreement on the contours" of a proposal set out by President Joe Biden in May.

Israeli Prime Minister Benjamin Netanyahu has expressed "cautious optimism" of progress, though one Israeli official said that "gaps" remain on sensitive topics, including whether or not Israeli forces will withdraw from key strategic areas within Gaza.

Meanwhile, the death toll continues to grow in the devastated strip. This weekend, more than 60 people were killed in Israeli airstrikes, according to the Hamas-controlled Health Ministry.

-ABC News’ Joe Simonetti and Tom Soufi Burridge

With a cease-fire deal "now in sight," President Joe Biden said in a statement Friday that "no one in the region should take actions to undermine this process."

Biden said his teams will "report to me regularly" as they remain on the ground over the coming days. Senior officials "will convene again in Cairo before the end of the week," he said.

The expectation is for a cease-fire to go into place soon after there is agreement between the parties, a source familiar with the talks told ABC News.

-ABC News' Justin Gomez