CRAWFORD, Texas - The White House, calling yesterday for a lasting cease-fire in the Mideast, backed Israel's air attacks on the Gaza Strip and said Hamas, which controls the area, had shown its "true colors as a terrorist organization."

After Hamas fired mortars and rockets deep into Israeli territory, Israel retaliated Saturday with a fierce bombing campaign - the deadliest against Palestinians in decades. The air strikes have enraged the Arab world.

"Right now the people of southern Israel are not able to live in peace," White House spokesman Gordon Johndroe said in Crawford, where President Bush is spending time at his ranch. "They have to live in bomb shelters a lot of the time. And that's unacceptable."

In Israel, 17 people have been killed in attacks from Gaza since the year began. A six-month truce between Hamas and Israel expired this month, but Hamas refused to extend it, saying Israel had violated its terms.

The United States urged Israel to avoid civilian deaths, yet that is difficult because bombs are falling in a tiny, crowded coastal area that is home to 1.5 million people. Johndroe expressed U.S. concern about humanitarian needs in Gaza, and said victims must be given access to food and medical supplies.

Asked if the United States thinks Israel is justified in its strikes on Gaza, Johndroe replied: "The United States understands that Israel needs to take actions to defend itself."

Bush spoke by phone with King Abdullah II of Jordan, who donated blood yesterday for Gaza victims. Bush, who took a call from King Abdullah of Saudi Arabia on Saturday, also received a daily intelligence briefing by secure video hookup and conferred with Vice President Cheney, White House chief of staff Joshua Bolten, and national security adviser Stephen J. Hadley.

By phone in Washington, Secretary of State Condoleezza Rice urged various parties to back a sustainable cease-fire. Spokesman Gordon Duguid said Rice had called her Israeli counterpart, Tzipi Livni, five times since Dec. 26.

He said Rice also had spoken with Israeli Prime Minister Ehud Olmert and Defense Minister Ehud Barak, Lebanese Prime Minister Fuad Saniora, and Russian Foreign Minister Sergey Lavrov.

Rice also called Egyptian Foreign Minister Ahmed Aboul Gheit three times and Saudi Foreign Minister Prince Saud al-Faisal, Duguid said.

Aides to President-elect Barack Obama said that Rice and her likely successor, Sen. Hillary Rodham Clinton, had been in contact, and that Obama would discuss the situation with Clinton and James Jones, his incoming national security adviser.

Senate Majority Leader Harry Reid (D., Nev.) and other lawmakers also expressed support for Israel's right to defend its citizens against rocket attacks from Hamas.

"As President-elect Obama has made clear time and again, no country should be forced to tolerate attacks on its people," said Sen. Frank Lautenberg (D., N.J.).

Hamas can choose to be a partner in peace, recognize Israel's right to exist, and renounce violence, Johndroe said. He would not speculate on how the United States would react if Israel, which has amassed tanks on the Gaza border, launched a ground invasion.

Johndroe said Obama was getting daily intelligence briefings. Bush had no immediate plans to speak publicly on the latest violence.

Bush had hoped for a peace accord before he left office, but that is far from a reality. The White House contends, however, that he has laid groundwork that will lead to a two-state solution to the decades-long conflict between Israel and the Palestinians in Gaza and the West Bank, which is ruled by the West-backed Palestinian Authority president, Mahmoud Abbas.

But Johndroe added, "Clearly with the Hamas actions in the last few days, it's not something that's going to advance in the immediate, near term."