WASHINGTON – The Hashemite king of Jordan is becoming nervous that a failing independent Palestinian Arab state may end up reuniting the East and West Bank of the river that divides his country from Israel.

King Abdullah is so nervous, one American diplomat said, that he has asked President Bush and Secretary of State Rice publicly to oppose an idea to federate a future Palestinian Arab state with his own kingdom.

That idea of a Palestinian-Jordanian federation is beginning to gain some momentum in Amman, Jerusalem, and Ramallah. On Tuesday, a former Jordanian prime minister and a recently departed interior minister of the Palestinian Authority endorsed the concept of a federation at an event sponsored by the American Enterprise Institute.

Even King Abdullah’s uncle, Hassan bin Talal, recently reiterated the view that the West Bank of the Jordan River is technically still Jordanian territory.

King Abdullah made it clear yesterday that Jordan was for Jordanians. “If there is anyone who believes that it is possible to settle the Palestinian issue at the expense of Jordan, he should know that Jordan will never be a substitute homeland for anybody, and that the Palestinians’ homeland and their state should be on Palestinian soil, and nowhere else,” he said.

Those words were in sharp contrast to what Prince Hassan told the UPI wire service on May 29. “I, for one, regard the Israeli-occupied territories as having been occupied from Jordan,” he said. “And for Jordan to say it relinquishes sovereignty is a legal lacuna, which recognizes the Israeli occupation, and that is unthinkable.”

An American diplomat this week said on condition of anonymity that King Abdullah has been “urging us to make a statement against federation. He has asked us personally to do this.” This diplomat said the response has been that President Bush’s mention of a two-state solution is a de facto rejection of a federated Palestinian-Jordanian entity.

The potential for a Palestinian-Jordanian federation is not merely a Hashemite family squabble or a diplomatic irritant in American-Jordanian relations. In the last six months a virtual civil war has intensified between the armed militias affiliated with the old bosses of the Palestinian Authority, Fatah, and the new ones, Hamas, whose party won a majority of seats in the legislative elections in January. So far not only has Hamas formally rejected pressure to recognize Israel’s right to exist, but it also has engaged in what at times looks like fratricide inside Gaza. Should the Israelis leave most of the West Bank, as Mr. Olmert has hinted he would do as early as this December, that fratricide would spread to Jordan’s border.

The idea of this federation is not particularly new. Between 1967 and 1988, King Hussein’s Jordan maintained legal and administrative ties in the West Bank territory Israel won in the Six-Day War. Jordan officially represented and hosted the Palestinian Arab delegation to the 1991 Madrid Peace conference. And Israeli leaders for many years have at times derisively referred to Jordan as the Palestinian Arab homeland.

“This is exploring and opening our minds to new options, given how the existing options have failed,” the vice president for foreign and defense policy studies at the American Enterprise Institute, Danielle Pletka, said. “Palestine is not even a state and it’s a failed state. It’s very understandable why this would be extremely unappetizing to King Abdullah.”

Ms. Pletka was one of the hosts at the Tuesday event, titled “A West Bank-Jordan Alliance?” The panel featured a former Jordanian prime minister, Abdul Salam al-Majali, as well as a former interior minister, Nasser Youssef. Both men endorsed an increased role for Jordan in the West Bank territories as part of an independent state. Also on the panel was a Princeton historian, Bernard Lewis, who gave a longer view of the status of Palestinian Arabs legally and culturally in the last 2,000 years.

“On the security track there might be a federal relationship with the Jordanian army. I do believe this relationship will be important because the Jordanians are not willing to negotiate instead of the Palestinians,” Mr. Youssef said. He added that this would be consisted with prior Palestinian National Council resolutions.

When asked if she was surprised at the opposition from King Abdullah, Ms. Pletka said she was not. “I can’t imagine we would wholesale announce the end of Jordan as we know it. I don’t see why the president would want to take this on.”