Cease-fire negotiations are "now in the end game," according to a senior U.S. official, who discussed what to expect over the next week as a deal is on the brink of finalizing.

The main elements of the proposal that President Joe Biden laid out on May 31 remain, but negotiators have taken the areas of disagreement and "bridged those in a way that we think basically is a deal that is now ready to close and implement and move forward."

"There is still more work to do, and over the course of this week, there are working group engagements to talk about everything from the list of hostages and the sequence by which hostages would be released, the list of Palestinian prisoners, because ultimately, this is an exchange, similar to what you saw in the November cease-fire deal," the official told reporters Friday.

Getting to this point has been "extremely complicated" and the portion of the deal focusing on the exchange of prisoners and hostages was a "large basis" of the talks in Doha, Qatar.

"There was some gaps there, and some trade space between the parties, which I think we've now gone a long way to bridge," the official said.

With tensions remaining high as Iran weighs a retaliatory attack on Israel, the official said if Iran really does want to see a cease-fire deal reached, "now is an opportunity to put their money where their mouth is and to basically work towards the conclusion of this."

"It's just ironic, it was Hamas, a proxy of Iran, started this war on Oct. 7, and it would be ironic if Iran were to do something to basically derail what we think is the best opportunity for the comprehensive cease-fire and hostage during these deal that we have had in many months."

President Joe Biden says negotiators are "closer than we've ever been" on reaching a deal and "much, much closer" than they were three days ago.

"We are closer than we ever been. I don't want to jinx anything," Biden told reporters in the Oval Office. "We may have something, but we're not there yet. But it's much, much closer than it was three days ago."

Three children have presented with suspected acute flaccid paralysis, a common symptom of polio, weeks after poliovirus was detected in environmental samples from Khan Younis and Deir al-Balah.

International aid groups are calling for temporary humanitarian pauses in order to launch polio vaccination campaigns across the Gaza Strip at the end of August and September to prevent the spread of the circulating variant type 2 poliovirus.

"During each round of the campaign, the Palestinian Ministry of Health (MoH), in collaboration with the World Health Organization (WHO), the United Nations Children’s Fund (UNICEF), the United Nations Relief and Works Agency for Palestine Refugees (UNRWA) and partners, will provide two drops of novel oral polio vaccine type 2 (nOPV2) to more than 640 000 children under ten years of age," the WHO and UNICEF said in a statement.

Hamas said it supports a humanitarian pause in order to vaccinate thousands of children against quadriplegia.

"At least 95% vaccination coverage during each round of the campaign is needed to prevent the spread of polio and reduce the risk of its re-emergence, given the severely disrupted health, water and sanitation systems in the Gaza Strip," the aid groups said.

A new "bridge proposal" was presented to Israel and Hamas, according to a joint statement from Qatar, Egypt and the U.S.

Israeli sources told ABC News progress has been made in negotiations and some of the gaps have narrowed. But Hamas said that the Israeli side did not abide by what was agreed upon on July 2 and Netanyahu even backed down from what was stated in the Israeli paper on May 27.

More talks will be held in Cairo next week to bridge the gap and complete the deal, the three countries said.

"Working teams will continue technical work over the coming days on the details of implementation including arrangements to implement the agreement's extensive humanitarian provisions as well as specifics relating to hostages and detainees," Qatar, Egypt and the U.S. said.

"There is no further time to waste nor excuses from any party for further delay," the countries said.