That's the rumor in both Washington DC and in Cairo at the moment, anyway. According to anonymous sources around the hostage talks, all of the mediating parties have just about given up on getting a deal done. The only tactic left to get an agreement is an ultimatum, apparently, and so the US, Egypt, and Qatar will issue one shortly.

'Take it or leave it' only applies to one of the two parties, of course, but the pressure will all come down on the other. And Israel knows it:

Israel is braced to receive a non-negotiable Gaza hostage deal on the table from mediating countries Qatar, Egypt and the United States.

“I think that what will happen in the end” is that “there will be a kind of take it or leave” deal which US President Joe Biden would put forward “together with the Egyptians and the Qataris,” Foreign Affairs and Defense Committee Chairman Yuli Edelstein told The Jerusalem Post on Tuesday morning.

“Then we will have to take a decision” because “it won’t be negotiable again,” he said.

This is going to be pointless, and the US already knows it. Israel keeps accepting terms proposed by the triumvirate, and Hamas refuses to budge. It won't cut any sort of deal that will keep it from re-arming and asserting control over Gaza again, and it's not even clear that they will meet the terms that they themselves have proposed, as Hamas often then changes them when Israel has tried to meet them.

Benjamin Netanyahu blasted his critics yesterday, including the White House indirectly, for demanding more concessions from Israel while Hamas murders the hostages:

“They shot them in the back of the head…and now, after this, we’re asked to show seriousness? We’re asked to make concessions? What message does this send Hamas? It says kill more hostages, murder more hostages, you’ll get more concessions,” Netanyahu stated.

“The pressure internationally must be directed at these killers, at Hamas, not at Israel. We say yes, they say no all the time. But they also murdered these people. And now we need maximal pressure on Hamas.

“I don’t believe that either President Biden or anyone serious about achieving peace and achieving their release would seriously ask Israel, Israel, to make these concessions,” he argued. “We’ve already made them. Hamas has to make the concessions.”

Exactly, but don't expect the new proposal to do any such thing. The Washington Post also reported late Sunday that the Biden administration will offer a "take it or leave it" plan, mainly as an escape hatch from the war. You have to get a miner's hat and a pickaxe to find the actual lede of the story, which is that the White House has finally begun to realize that Hamas isn't taking any of these negotiations seriously. You have to get through 15 paragraphs of obfuscation before finding out why the triumvirate will soon wash their hands of this:

Some Middle East experts said that the fewer living hostages there are, the less pressure there will be on Netanyahu to come to a deal — U.S. officials fear the number of living hostages may number only in the dozens.

The senior administration official said Hamas’s decision to execute the hostages with negotiations under ways “calls into question” Hamas’s seriousness in the talks. Hamas has proved obstinate at various points in the talks, even as Israeli officials have made concessions, the official said.

At the very same moment, Biden came out of his beach chair to accuse Netanyahu of not doing enough to get a deal done. He knows, as does Antony Blinken and the rest of the foreign-policy team, that Netanyahu has accepted several American formulas for a pause even though the terms cut against their preferred war policies. The problem has never been Israel -- it has always been Hamas. And yet Biden lies about it even as his own team has begun to concede that Hamas has never been serious about these negotiations in the first place.

It's despicable. Biden wants to settle some old scores with Netanyahu as well as shore up his party's prospects in Michigan, and he doesn't care about damaging Israel's national security to do so. 

If the proposal includes an Israeli withdrawal from the Philadelphi Corridor, then Israel may leave it before Hamas has the chance. Netanyahu also made clear that he has no intention of allowing Hamas to re-arm through Philadelphi, and that pulling out 20 years ago was a massive mistake that he has no intention of repeating:

Once Israel left the Philadelphi Corridor in 2005 during the Gaza pullout, there was a “massive introduction of weapons, munitions, machines for producing weapons and machines for digging tunnels - all sponsored by Iran, directed by Iran, financed by Iran.”

That “axis of evil” needs to regain control of  Philadelphi Corridor, Netanyahu said, adding that “Hamas insists for this reason that we will not be there, and for this reason, I insist that we will be there.” ...

He said that once Israel leaves the Philadelphi it will never be allowed to return, explaining that in the end, this wasn’t purely a military issue, but also a diplomatic one that had to take into account broader strategy.This isn’t a security issue, this is about a national geopolitical strategy,” he said.

Will that force the US to walk away from negotiations? Probably, and that might be best for Israel. Over the last 20 years, the US has intervened several times to freeze this conflict between Hamas and Israel on the assumption that Hamas would eventually start becoming a serious governing party rather than the terrorist proxy army it has been all along. Now the US wants to return to the frozen-conflict status quo that Hamas breaks over and over again. It will be better in the long run for this war to get settled as wars do -- with either capitulation, complete destruction, and/or the discrediting of the warmakers.