By Steve Holland and Patricia Zengerle
WASHINGTON (Reuters) - President Joe Biden and aides worked behind the scenes on Monday pressing for a ceasefire between Israel and Hamas amid what one source said was frustration over Israel's bombing of a Gaza building that housed some news organizations.
Biden is facing growing pressure from lawmakers in his own Democratic Party to play a more vocal role, but U.S. officials say he and his team have opted for a quieter effort, talking with Israeli officials and U.S. allies in the Arab world.
"Our calculation at this point is that having those conversations behind the scenes ... is the most constructive approach we can take,” White House spokeswoman Jen Psaki told reporters.
Biden spoke by phone with Israeli Prime Minister Benjamin Netanyahu, their third conversation since the violence erupted.
The White House said Biden "encouraged Israel to make every effort to ensure the protection of innocent civilians" and that the two leaders "discussed progress in Israel’s military operations against Hamas and other terrorist groups in Gaza."
"The president expressed his support for a ceasefire and discussed U.S. engagement with Egypt and other partners towards that end," a White House statement said.
Supporters of the Biden administration demanded quicker action.
“We’re really frustrated that the administration is not moving with more urgency,” said Logan Bayroff, spokesman for J Street, a liberal pro-Israel lobbying group.
Twenty-eight senators - more than half of the Democratic caucus - issued a statement on Sunday calling for an immediate ceasefire "to prevent any further loss of civilian life and to prevent further escalation of conflict."
Senate Majority Leader Chuck Schumer said on Monday he also wanted to see a ceasefire reached quickly.
The Biden administration has increasingly relied on Egypt because of its influence with Hamas, whose rocket barrages into Israeli cities have prompted a fierce response from Israel and led to the biggest outbreak in hostilities since 2014.
The administration would like to get on a glide path to de-escalation in coming days, leading to what a source familiar with the situation called a humanitarian pause in the violence to let relief assistance be delivered to Gaza and build a sustainable calm.
The United States was believed to be preparing significant initiatives on Gaza humanitarian reconstruction, the source said.
'IMPERATIVE TO RESTORE CALM'
Biden has strongly defended Israel's right to defend itself because of the repeated rocket barrages from Hamas, which the United States views as a terrorist organization.
But the administration did not support Israel's destruction of a Gaza high-rise that housed the Associated Press and Al Jazeera offices.
The Biden administration viewed the strike on the building as a major strategic mistake, particularly because it turned some public opinion against Israel in the United States, the source said.
The Gaza building attack has prompted some Democratic lawmakers to call foul.
“The increasing loss of civilian lives of Palestinians and Israelis is unconscionable and unacceptable," said Democratic Representative Joaquin Castro. "I’m particularly disturbed by the disproportionate bombing of the Gaza Strip, including the deaths of at least 92 women and children and the targeting of the Associated Press building."
Secretary of State Antony Blinken tweeted that he had spoken to United Arab Emirates Foreign Minister Abdullah bin Zayed Al Nahyan about the urgent need to halt the violence in Israel and the West Bank and Gaza.
"The loss of life from this crisis is deeply saddening, and it is imperative to restore calm and end this conflict," he said.
The Biden administration has privately blamed the administration of Republican former President Donald Trump for breaking off communications with the Palestinian Authority in its zeal for a pro-Israel policy, believing that has contributed to instability.
While Trump helped negotiate four normalization deals between Israel and Arab countries, he cut assistance to the Palestinians.
(Reporting by Steve Holland and Patricia Zengerle; Editing by Mary Milliken and Peter Cooney)