Updated at 9:20 p.m.

In an unusually frank speech for America’s top diplomat, Secretary of State Kerry issued an impassioned warning on Wednesday: The expansion of Israeli settlements in the West Bank is in danger of becoming a tipping point.

If it continues, the hope of any two-state solution – one on which the whole peace process rests, in his eyes – could die.

That, he said, was the reason behind President Obama’s decision not to shield Israel from last week’s United Nations Security Council vote, which condemned Israeli settlements as illegal and an obstacle to peace.

But the speech in many ways seemed to reflect his own wrestling with the fact that a growing number of Israelis and especially Palestinians have already given up hope that a two-state solution can be achieved.

On the Israeli side, the pro-peace camp has atrophied after years of US-brokered negotiations and Israeli withdrawals from Lebanon and the Gaza Strip failed to end the conflict with their Arab neighbors. Many see the US as naïve, advocating idealistic moves that Israel views as foolhardy in a region beset by radical Islamist terrorism.

For Palestinians, the steady growth of the Israeli settler population – which has nearly quadrupled in the West Bank since the Oslo Accords produced a blueprint for the two-state solution in the 1990s – proves Israel is not serious about making peace.

They see America’s support for Israel – including a 10-year, $38 billion military aid package signed this year – as insupportable amid Israel's continued occupation of Palestinians, whose travel, trade, businesses, and rights are restricted by Israel.

"John Kerry just gave an eloquent eulogy for the two-state solution,” said Ali Abunimah, director of the Electronic Intifada website, in comments distributed by the pro-Palestinian Institute for Middle East Understanding (IMEU) in Washington.

“His detailed critique of Israeli settlements and occupation was striking in its forthrightness – rare from US officials," he continued. "But it serves more than anything as an indictment of the United States, which funded, enabled and protected the brutal reality Palestinians have lived under for so long.”

Mr. Abunimah, author of the 2006 book, "One Country: A Bold Proposal to End the Israeli-Palestinian Impasse," instead advocated a “democratic, decolonized one-state solution with equal rights for all.”

He’s not the only one. While a slim majority of Israelis and Palestinians still support the two-state solution in principle, the trendlines are moving against it, in some cases dramatically. According to an August poll conducted jointly by Israelis and Palestinians, a quarter of Israelis and 35 percent of Palestinians now support a one-state solution.

Since then, there are signs that settlement construction has had a further effect on public opinion among Palestinians. There has been a “sharp increase in the percentage of those who [believe] that the two-state solution is no longer viable due to settlement expansion from 56% three months ago to 65%,” according to a December poll by the Palestinian Center for Survey and Policy Research, a respected polling outlet in Ramallah, West Bank.

More than 8 in 10 respondents said the Obama administration had not made “serious efforts” to advance peace – despite Kerry’s year of peripatetic shuttle diplomacy in 2014.

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Likewise, there’s been a dramatic drop in optimism among the Palestinian minority in Israel, which accounts for about one-fifth of the population. From 2013 to 2015, Israeli Arabs who viewed the two-state solution as possible dropped from 72 percent to just 50 percent, while it declined only slightly among Israeli Jews to 43 percent.

In his speech, Kerry implored both sides to reenergize the push for a two-state solution, insisting that “there is still a way forward if the responsible parties are willing to act.” But the subtext was an admission that the support for the blueprint itself might be fraying.