JERUSALEM — For Mahmoud Abbas, the ailing octogenarian president of the Palestinian Authority, his life’s work — a viable state side-by-side with Israel — is quickly slipping away.

President Trump’s Middle East plan deprives the Palestinians of nearly everything they had been fighting for: East Jerusalem as their national capital, the removal of Jewish settlements on the West Bank, and territorial contiguity and control over their own borders and security that a sovereign state normally enjoys.

While it was always presumed that such a state would be forged through talks with the Israelis, years of failure, a weak and divided Palestinian leadership, and an Arab world that has largely moved on have all emboldened Mr. Trump and Prime Minister Benjamin Netanyahu of Israel to try to impose a solution of their own.

The landscape has shifted so much in recent years that Mr. Abbas has few good options.

With only muted reaction from Arab neighbors, a struggling Palestinian economy, little apparent appetite among Palestinians for a violent response and the United States having abandoned any pretense of neutral mediation, a proposal that might have been considered outlandish a decade ago landed with little serious opposition.