JERUSALEM — Two senior White House envoys arrived Tuesday for meetings with Israeli and Palestinian leaders in a last-ditch effort to head off a Palestinian bid for recognition of statehood at the United Nations this month.

David Hale, the Obama administration’s acting special envoy to the Middle East, and Dennis Ross, the president’s Middle East adviser on the National Security Council, are pressing for a resumption of peace negotiations that were broken off a year ago.

But their prospects for success appear dim, with aides to Palestinian Authority President Mahmoud Abbas ruling out any change of plans to seek recognition of a Palestinian state at the U.N. General Assembly session beginning Sept. 20.

“From our point of view, it’s out of the question,” said Nabil Shaath, a senior aide to Abbas. “It’s much too late for that.”

Shaath said that at this stage, it would be politically “suicidal” for Abbas to reverse himself, after preparing the Palestinian public for months for the U.N. bid.“How can we ask our people to believe that we are really serious?” he said.

The initiative at the United Nations “is definitely not a substitute for negotiations,” Shaath added, saying that the Palestinians are prepared to resume talks if Israel freezes its settlement building in the West Bank and agrees to negotiate a solution based on Israel’s 1967 boundaries.

At a meeting with left-wing Israeli academics and writers on Monday, Abbas said that negotiations remained the only way to resolve the conflict, regardless of the outcome at the United Nations.

Israeli Prime Minister Benjamin Netanyahu, who agreed to a 10-month settlement-building freeze that expired last September, has rejected any further suspension of new construction and says the Palestinians should recognize Israel as the Jewish state, a demand they reject.

Washington has opposed U.N. recognition of a Palestinian state, calling it a unilateral step in a conflict that should be resolved by negotiations. The administration has made clear that it would veto any Palestinian request to the Security Council for membership as a state. But a majority at the General Assembly is expected to support the promotion of the Palestinians to the status of a nonvoting observer state.

Netanyahu warned Monday that the Palestinian bid for U.N. recognition would “set back peace, and might set it back for years.”