The Bush administration on Tuesday blamed terrorists based in Syria (search) for last week's deadly attack in Israel and called for an immediate end to Syrian military and political domination over neighboring Lebanon.

Secretary of State Condoleezza Rice (search) applied the strongest American pressure on the Syrians to date, saying at an international conference in London that they were "out of step" in the Middle East and there was growing international resolve against them.

In Washington, White House press secretary Scott McClellan said, "We do have firm evidence that the bombing in Tel Aviv was not only authorized by Palestinian Islamic Jihad (search) leaders in Damascus, but that Islamic Jihad leaders in Damascus participated in the planning."

President Bush made a similar point during a White House meeting with congressional leaders, participants said, and so did Rice.

An explosion triggered by a bomber outside a Tel Aviv nightclub Friday night killed five people. It also shook a cease-fire declared by Israeli and Palestinian leaders, in which militant Palestinian group leaders had agreed to a temporary halt to attacks.

As for Lebanon, all key Lebanese political decisions are assumed to have a stamp of approval from the government of Syrian President Bashar Assad (search).

Huge street demonstrations and Monday's resignation of the pro-Syrian Lebanese government marked the most serious challenge to Syrian authority in Lebanon since the end of the civil war that killed 150,000 and crushed the Lebanese economy in the 1970s and 1980s.

The events also were an opening for the Bush administration to press its wider goal of democracy across the Middle East and to throw a spotlight on what the United States contends is Syrian support for terrorists who are trying to undermine progress toward Israeli-Palestinian peace and in Iraq.

"The Syrians are out of step with where the region is going and out of step with the aspirations of the people of the Middle East," Rice told reporters following the conference on Palestinian security and political reform.

Rice said there is a new international consensus that Syria must withdraw from Lebanon, pointing to a joint U.S.-French statement on Tuesday and a United Nations resolution last fall. Her point was further underscored when Russia on Tuesday joined Saudi Arabia and Egypt in pressing for a withdrawal. "I think it's one of the strongest statements in a long time about what needs to happen in Lebanon," Rice said.

She also said the Lebanese should be allowed to choose their own political future independent of "contaminating influences."

At a press conference with French Foreign Minister Michel Barnier, Rice said their two countries would support the scheduled election in Lebanon, perhaps by sending observers and monitors.

She also suggested international peacekeepers might be needed eventually and could help secure democracy for the Lebanese if the Syrians withdraw their thousands of troops and security forces.

"As we see how the Lebanese will move forward I think we have to look at what can be done in terms of helping them to stabilize the situation, should that become necessary," Rice said.

She gave no details, and later said it was too soon to talk about the specifics of security in Lebanon after a hypothetical Syrian withdrawal.

In Washington, Senate Foreign Relations Committee Chairman Richard Lugar, R-Ind., said after the meeting with Bush that there was consensus among Democratic and Republican leaders in the room that "Syria must go."

Sen. Joe Biden of Delaware, the committee's senior Democrat, agreed. "Their only friend in the region is Iran. They should get out" of Lebanon, Biden said.

An Israeli diplomat said his government had shared information with Washington regarding the allegation of the involvement of the Damascus-based Islamic Jihad in the Tel Aviv attack.

Rice said international pressure on Syria was working, and the United States probably would not ask for further international sanctions or other strong measures — for now.

"The pressure of the international community is quite palpable on Syria," she said.

The United States pulled its ambassador from Damascus last month in protest over the assassination of a leading Lebanese politician. The Bush administration did not blame Syria outright for Rafik Hariri's killing.

The bombing that killed him in Beirut on Feb. 14 set off a popular uprising against Syria and a series of apparent concessions from Damascus, which keeps about 15,000 troops in Lebanon. In recent days, Syria has abandoned the pro-Syrian Lebanese prime minister, announced troop shifts at home and turned Saddam Hussein's half brother over to Iraq.

Gen. John Abizaid, the top U.S. military officer in the Mideast, also told the Senate Armed Services Committee on Tuesday that the Syrian government had made some effort to stop anti-U.S. fighters infiltrating across their border into Iraq.

However, said Abizaid: "I don't regard this effort as being good enough. ... I cannot tell you that the level of infiltration has decreased."

The British-led conference Rice attended was meant to strengthen the government of newly elected Palestinian President Mahmoud Abbas, on whom the Bush administration has pinned some of its hopes for the region.