Ultimately, a successful Palestinian state will need to have all its people, from both the West Bank and Gaza, working together to build a stable and prosperous future. The recent agreement between the two main factions — Fatah, which leads the Palestinian Authority and has committed to peace with Israel, and Hamas, which has committed to Israel’s destruction — is not the answer.

We have many concerns about the accord, starting with the fact that Hamas has neither renounced its legacy of violence nor agreed to recognize Israel. The Palestinian Authority president, Mahmoud Abbas, has said he remains in charge of peace efforts and the unity government will be responsible for rebuilding Gaza and organizing elections. Whether that is Hamas’s vision is unclear.

Also disconcerting are suggestions that Mr. Abbas may have privately agreed to replace his prime minister, Salam Fayyad, who has done so much to build up the West Bank economy and institutions. There are big questions about the future of the two sides’ security forces.

The United States has spent millions of dollars helping the Fatah-led Palestinian Authority create a security force that Israel has come to rely on to keep the peace in the West Bank. Whether Hamas, which has terrorized Israel with rockets from Gaza, can ever be integrated into that force, or even work side by side, is a huge question.

Israel certainly has many reasons to mistrust this deal. Prime Minister Benjamin Netanyahu has suspended tax remittances and is pressing Washington hard to cut off aid to the Abbas government. The Obama administration has reacted warily to the new pact but said its assistance will continue for now. Congress is talking tough.

It’s too early for a cut-off. The money is Washington’s main leverage on the new government. A cut-off would shift the political balance dangerously toward Hamas.

Other reconciliation attempts between Fatah and Hamas have imploded, but Mr. Abbas seems to believe this will advance his push to get the United Nations General Assembly to recognize a Palestinian state. Above all, his sudden willingness to deal with his enemies in Hamas is a sign of his desperation with the stalled peace process.

Hamas’s goals are far harder to game, although there are reports of new frictions with Syria and a desire for better ties with Egypt’s new government. In an interview with The Times last week, Khaled Meshal, the Hamas leader, declared himself fully committed to working for a two-state solution. Just a few days earlier Hamas’s (supposedly more moderate) prime minister, Ismail Haniya, was out there celebrating Osama bin Laden as a “Muslim and Arab warrior.” Huge skepticism and vigilance are essential. But more months with no progress on peace talks will only further play into extremists’ hands.

So what happens now? The United States and the other members of the quartet — the European Union, Russia and the United Nations — need to put the new government on notice that all support will be carefully scrutinized and that firing Mr. Fayyad would be a big mistake. They need to tell Hamas that if it is serious about coming in from the cold, it must halt all attacks on Israel and recognize its right to exist.

At the same time Washington needs to press Mr. Netanyahu back to the peace table. A negotiated settlement is the only way to guarantee Israel’s lasting security.

For weeks President Obama and his aides have been debating how to revive the peace process — and how deeply the president should engage. (His peace envoy has not even been in the region for five months.)

The answer, to us, is clear. It is time for Mr. Obama, alone or with the quartet, to put a map and deal on the table. If Bin Laden’s death has given the president capital to spend, all the better. The Israelis and Palestinians are not going to break the stalemate on their own. And more drift will only lead to more desperation and more extremism.