JERUSALEM — Despite seemingly premature congratulations from President Barack Obama, Israel's prime minister was scrambling Monday to secure enough Cabinet votes to pass a U.S. proposal to halt West Bank settlement construction for 90 days, aimed at restarting peace talks with the Palestinians.

Benjamin Netanyahu is under heavy pressure to move forward with the plan, which could lead to critical negotiations on Israel's final borders with a future Palestine.

Although Israeli officials say the plan includes an unprecedented gift of 20 stealth warplanes to Israel, Netanyahu faces opposition from hard-liners inside his coalition government who oppose limits on settlement construction in principle and fear it will create pressure for further concessions.

Palestinians didn't embrace the plan either, since the proposed building freeze wouldn't include east Jerusalem, their hoped-for capital, and Israel would be rewarded for what they see as a minimal gesture.

It appeared increasingly unlikely, however, that both sides, wary of upsetting Obama, would risk turning down the package. Officials said Netanyahu's 15-member Security Cabinet — a grouping of senior Cabinet ministers — would soon meet to vote on the proposal, possibly as early as Wednesday. The measure appeared poised to squeak through 7-6, with two ministers abstaining.

Opponents were gearing up as well. Yuli Edelstein, a Cabinet minister from Netanyahu's Likud Party, convened a group of hard-line lawmakers and settler leaders to battle the proposal.

"We have 48 hours to operate," Edelstein said. "Any decision made by Israel is a one-way decision, and we have no way out."

Adding pressure on the Israeli leader, Obama commended Netanyahu late Sunday for considering the slowdown. "It's not easy for him to do, but I think its a signal that he is serious," he said.

In another sign of difficulties in the process, State Department spokesman P.J. Crowley said Monday that Obama's September deadline for a peace accord may not be realistic. He said the administration still believes a deal can be reached in a "reasonable period of time." He did not elaborate.

The U.S. has been working for more than a month to revive Israeli-Palestinian peace talks, which opened with great fanfare at the White House in early September but broke down weeks later with the expiration of a 10-month Israeli slowdown on settlement construction.

The Palestinians say they cannot return to the negotiating table now that Israel has resumed settlement construction. They say it is a sign of bad faith if Israel insists on building on captured territories that the Palestinians claim for their future state.

Netanyahu has said the issue of Jewish settlements should be determined in negotiations.

Israeli officials disclosed initial details of the U.S. compromise on Sunday, saying that Netanyahu had worked it out during a seven-hour meeting with Secretary of State Hillary Rodham Clinton in New York last week.

The highlights include giving Israel a gift of 20 F-35 stealth jets, worth about $3 billion — in addition to 20 of the next-generation warplanes Israel has already ordered for purchase. It would mark the first time the U.S. has given warplanes to Israel without payment, defense officials and diplomats said.

Also in the deal are American guarantees that the U.S. would veto anti-Israel resolutions at the United Nations. With the Palestinians threatening to take their case to the U.N. if peace talks fail, this protection could be critical for Israel down the road.

While the U.S. routinely vetoes resolutions critical of Israel, American vetoes are not automatic, and some Israelis were uncertain Obama would back it at the Security Council. Cabinet Minister Dan Meridor told Israel's Channel 10 TV on Monday that U.S. veto protection against unilateral Palestinian U.N. initiatives would last for a year.

In return, Israel would halt most construction in the West Bank for 90 days, with the understanding that both sides would use the time to set their future border.

A border deal would presumably make the settlement dispute moot, since Israel could resume construction on all territory it expects to keep while halting building in areas on the Palestinian side.

While Netanyahu has said little publicly, both Israeli and American officials say he supports the compromise and is trying to win Cabinet approval.