President Joe Biden on Thursday pledged humanitarian and reconstruction aid for Gaza as he hailed a deal to end 11 days of fighting between Israel and Hamas that tested his negotiating skills and exposed him to criticism from fellow Democrats.

Biden, appearing briefly at the White House after news of the ceasefire agreement, also promised to replenish Israel's Iron Dome missile defense system, despite complaints from the Democratic left about a pending U.S. arms sale to Israel.

Biden said the United States would work through the United Nations and other international stakeholders "to provide rapid humanitarian assistance and to marshal international support for the people in Gaza and in the Gaza reconstruction efforts."

He insisted that reconstruction aid would be provided in partnership with the Palestinian Authority and not with Hamas, which the United States labels a terrorist organization.

The Palestinian Authority, which is run by moderate President Mahmoud Abbas, only governs parts of the occupied West Bank, however, while Hamas holds sway in the Gaza Strip.

"We will do this in full partnership with the Palestinian Authority - not Hamas - in a manner that does not permit Hamas to simply restock its military arsenal," Biden said.

State Department spokesman Ned Price said Secretary of State Antony Blinken would travel to the region in coming days to meet Israeli, Palestinian and regional counterparts to discuss recovery efforts and "working together to build better futures for Israelis and Palestinians."

The ceasefire agreement followed days of intense diplomatic activity that provided a test of the ability of Biden and his top national security aides to help resolve a conflict that could have spiraled into a prolonged war.

During the negotiations, Biden spoke to two leaders with whom he has had tense relations - six times with Israeli Prime Minister Benjamin Netanyahu, including twice on Thursday, and once with Egyptian President Abel Fattah al-Sisi.

Both Netanyahu and Sisi were close to Biden's Republican predecessor, Donald Trump. Biden waited weeks to call Netanyahu after taking office in what Israel viewed as a snub.

His phone call with Sisi on Thursday was the first time they had spoken since Biden took office in January. Egypt, which has a peace treaty and diplomatic relations with Israel and also maintains contacts with Hamas, has traditionally played a key role in quelling Gaza fighting.

The absence until now of direct communication between the two presidents had been widely seen as a snub of Sisi by a new administration that has made clear its concerns about Egypt’s human rights record.

When the conflict began, the administration was cautious not to make public demands of Israel out of concern Israelis would ignore U.S. appeals and prolong the conflict, a source familiar with the behind-the-scenes negotiations said.

The United States got a sense five or six days ago that Israel was prepared to begin a wind-down phase after destroying much of the Hamas targets it had set out to hit, the source said.

At that point, senior U.S. officials from Biden on down began pressing Israel more strongly for a de-escalation and a ceasefire, the source said.

On Thursday, Israel signaled to Biden officials a readiness for a ceasefire, the source said. The United States informed Egypt, which told Hamas.

The Islamist militant group then informed Egypt of its readiness for a ceasefire, and Egypt informed the United States. The main interlocutor for Egypt was Cairo's intelligence chief, the source said.

Whether the truce would hold was a major concern, with the United States not making any guarantees given fears of more random rocket attacks and other tensions between Israelis and Palestinians, the source said.

The Hamas rocket attacks followed Israeli security police clashes with worshippers at al-Aqsa Mosque in Jerusalem and a court case by Israeli settlers to evict Palestinians from a neighborhood in Israeli-annexed East Jerusalem.

If the evictions go ahead, the source said, that could become a new flashpoint, so U.S. officials are discussing the matter with the Israelis.

Biden's public backing of Israel's right to self-defense against Hamas rocket attacks prompted criticism from fellow Democrats that he needed a more balanced approach instead of marching in lockstep with Israel.

In his remarks, Biden defended his approach to handling the crisis but gave a nod to his critics, saying Palestinians deserve to live in peace and security just like Israelis.

"My administration will continue our quiet, relentless diplomacy toward that end. I believe we have a genuine opportunity to make progress and I am committed to working for it," he said.

With some critics pointing to Biden’s lack of high-level representation on the ground, the source made clear that the selection of a new U.S. ambassador to Israel was nearing an end.

Thomas Nides, a former State Department official who is currently a Morgan Stanley (MS.N) executive, and Robert Wexler, a former Democratic lawmaker with extensive Middle East experience, are the front-runners, a U.S. official told Reuters recently.

The Axios news website reported on Thursday that Biden was leaning toward picking Nides, citing a source familiar with the process.