Obama has offered a formula to Israel, for land changes "based on the 1967 lines with mutually agreed swaps", which is a poison pill for Israel.
The part that becomes deadly afterward is that before the negotiations start, Obama wants Israel to agree to the 1967 lines as a basis for negotiation. In effect he is saying: "Accept this formula, and some time later I will explain to you what your obligations are according to this formula".
The Jordanians have no interest in returning to claim the territory that they conquered and held from 1948-1967, so it means turning over the territory to the Hamas-Fatah partnership. That is, promising to give up the Western Wall, the Jewish Quarter of the Old City, the Temple Mount, half of Jerusalem, expelling the 250,000 Jews living in Jerusalem in the area targeted by the ethnic cleansers and their helpers, all of Judea and Samaria, and the 320,000 Jews living in Judea and Samaria. It means indefensible borders reducing Israel to 9 miles in width. It means that Israel gives up a military presence along the Jordan River, which was demanded in Obama's statement about a complete withdrawal of Israeli forces. It means a disastrous, perilous situation for Israel, and a demand for that will be coming when that phase of the poison pill takes effect.
After Israel agrees to the poison pill formula, the negotiations will become deadlocked, because it profits the Palestinians to produce a deadlock which will reward them with the 1967 lines. For example, the jihadists of Hamas will welcome obtaining the Western Wall from Israel, the Jewish Quarter of the Old City (with its Jewish residents expelled), and complete control over the Temple Mount. Even if Israel offered half of pre-1967 Israel in an effort to ransom the holy places, this will not be good enough for Hamas (although it would be a disaster in itself for Israel to offer such a ransom). The deadlock will cause Obama to spring into action, and accuse Israel of reneging on its promise, unless it agrees to go to the 1967 indefensible borders. He will say something like: "The United States does not accept the legitimacy of Israel's refusal to go back to the 1967 borders." He will get the international community to back his threat that Israel will be isolated in the world if it doesn't go back to the 1967 borders. He will say that Israel has reneged on its promise, and is therefore in violation of international law. He will say that this behavior by Israel is an insult to the U.S. He will say that this behavior is causing instability in the world, and causing American deaths.
Mr. Obama tries to move into his plan gradually, not all at once. But once Israel agrees to accepting a return to the 1967 lines as a basis for negotiation, Israel will have legitimized this concept of returning to the 1967 lines, and will open itself for the next phase, which will come when there is a deadlock. That phase is the demand, backed by threats by Obama and the international community, for Israel to go back to the 1967 lines.
The maximum pressure on Israel will come during Obama's second term. He will not exert maximum pressure during his first term, because Jews contribute more than 50% of the donations received by Democrats running for political office (even though they are nationally a small percentage of the total number of voters). He will not exert maximum pressure during his first term, because in the key battleground state of Florida, with 29 electoral votes and a history of switching between the parties in different elections, the significant Jewish vote there could make a difference that affects which presidential candidate wins Florida's 29 electoral votes, a sizable amount. But after the November 2012 election, he will feel free to exert all the pressure he likes against Israel. And that's when the poison aspect of the poison pill will start to be felt.
Accepting, and therefore legitimizing, a plan involving a return to 1967, whether as a goal for negotiations, or as the starting point of negotiations, or as the official mediator's position, or as a basis for negotiations, would be an invitation to disaster for Israel. When a deadlock in the negotiations occurs, that 1967 situation would become the default, and it would be demanded that Israel go back to 1967.
