A handout photograph supplied by the Palestinian Authority on Wednesday shows U.S. Secretary of State John Kerry, center left, meeting with Palestinian President Mahmoud Abbas in Amman, Jordan. (Thaer Ghanaim / Handout/European Pressphoto Agency)

— Facing the possible collapse of his signature Middle East peace effort, Secretary of State John F. Kerry interrupted a European diplomatic trip to meet face to face Wednesday with a Palestinian leader who has threatened to walk out of the negotiations.

Kerry met with Palestinian Authority President Mahmoud Abbas in the Jordanian capital, where the Palestinian leader has a home. Kerry flew to Amman from Rome early Wednesday and spoke en route to Israeli Prime Minister Benjamin Netanyahu.

At issue is the scheduled release this weekend of a final group of Palestinian prisoners long held by Israel and how to salvage eight months of talks if that promised release is delayed or canceled.

Abbas is under heavy domestic political pressure to walk away from the U.S.-backed peace effort if Israel does not complete the release of the 26 Palestinian prisoners by March 29 as agreed at the outset of talks last summer.

Arab leaders blamed Israel on Wednesday for the lack of progress in the peace negotiations and declared that they would never recognize Israel as a “Jewish state,” one of Israel’s demands to resolve the conflict.

“We express our absolute and decisive rejection to recognizing Israel as a Jewish state,” the Arab League said in an official communique at the conclusion of a two-day summit in Kuwait. It was no surprise that the group opposes recognizing Israel as a Jewish state: Of the league’s 22 members, only Jordan and Egypt keep diplomatic relations with Israel.

In recent months, Netanyahu has pressed Kerry to push the Palestinians to recognize Israel as the homeland of the Jewish people.

Abbas and his negotiators have said that it is enough that the Palestinians recognize Israel as a state and a partner in the peace deal. To recognize Israel as a Jewish state, they say, undermines the rights of more than 20 percent of the Israeli population who are Muslim and Christian.

For his part, Netanyahu says that until the Palestinians, and the Arab world, acknowledge that the Jews have a right to a state in the Middle East, there will never be lasting peace.

Kerry met for lunch with Jordan’s King Abdullah II, who has served as a back-door emissary to Palestinians during talks the secretary launched with great difficulty. The goal is a detailed framework for a peace treaty next month that would be the template to resolve more than 60 years of enmity and decades of Israeli occupation.

U.S. officials refused to discuss Kerry’s meetings in depth, but State Department spokeswoman Jen Psaki disputed Israeli news media claims that current discussions include the early release from a U.S. prison of convicted Israeli spy Jonathan Pollard.

“Pollard was convicted of espionage against the United States, a very serious crime,” Psaki said Wednesday. “There are currently no plans to release Jonathan Pollard.”

Netanyahu and other Israeli leaders have long sought the release of the former U.S. intelligence analyst, who was convicted in 1987 of passing secrets to Israel and sentenced to life in prison. Pollard’s early release could sweeten the prisoner release — a bitter political issue for Netanyahu — by mollifying hard-line members of his political coalition.

Israel wants Palestinian leaders to agree to extend the talks before it carries out the prisoner release. Israeli officials have suggested the release of the last of four groups of Palestinian prisoners may be delayed or canceled. They blame Palestinians for changing the terms or failing to negotiate seriously as Kerry’s self-imposed deadline for an outline approaches at the end of April.

It is not clear what Kerry would do if either side walked out.

Kerry is expected to rejoin President Obama’s trip to Rome and Saudi Arabia on Thursday. Obama’s trip has been dominated by the standoff with Russia over Crimea and Ukraine.

The State Department announced Wednesday that Kerry will travel next week to Brussels to meet with NATO foreign ministers. That session is also expected to focus on Russia and Ukraine. Kerry will also visit Algeria and Morocco next week.

Booth reported from Jerusalem.