JERUSALEM (AP) — A White House official said Tuesday that Egypt, Jordan and Morocco have confirmed their attendance at a U.S. conference this month in Bahrain, where it will unveil the economic portion of its long-awaited plan for Mideast peace.

The positive responses from key Arab states delivered a diplomatic victory for the U.S., which faces tough resistance to its proposed solution to the Israeli-Palestinian conflict.

The Palestinians, citing the Trump administration’s pro-Israel bias, have already said they will not attend the summit and have rejected the peace plan out of hand.

The White House hailed the countries’ attendance as “welcome news,” a sign “that our workshop is gathering momentum as we had anticipated.”

The level of their representatives was not immediately known, but the U.S. had extended invitations to finance ministers. Saudi Arabia, Qatar and the United Arab Emirates are already scheduled to attend.

Presidential advisers Jared Kushner and Jason Greenblatt made personal appeals to the kings of Morocco and Jordan during their recent Mideast trip to rally support for the plan.

Egypt and Jordan, as U.S. allies and the only Arab countries that have peace agreements with Israel, occupy delicate political positions. Their leaders often voice support for a two-state solution to the conflict, which remains the only internationally accepted option but appears to be at odds with the little that has been revealed about Trump’s “Deal of the Century.”

Jordan, which acts as custodian of Muslim holy sites in Jerusalem and is home to more than 2 million Palestinian refugees, has long been invested in a solution to the most sensitive issues of the decades-old conflict. Egypt, which shares a border with the blockaded Gaza Strip, is also a key regional player.

The U.S. is hoping to draw Arab states with deep pockets to participate in the workshop, which envisions large-scale infrastructure work and investment in the Palestinian territories.