Rice deferred to the decisions of President Bush and military commanders as Republicans and Democrats on the Senate Foreign Relations Committee pressed her for more specifics on the U.S. strategy in Iraq.

Asked specifically whether the United States would have troops in Iraq in five or 10 years, Rice said: "I think that even to try and speculate on how many years from now there will be a certain number of American forces is not appropriate."

Lawmakers also pressed her on strategy for dealing with Iran and Syria. U.S. officials have accused Syria of allowing foreign fighters to flow across its borders into Iraq and Iran of supporting the insurgency.

Rice said the United States was using diplomatic means to urge a change in the behavior of both countries-- but she stopped short of ruling out military force. "I'm not going to get into what the president's options might be," Rice said. "I don't think the president ever takes any of his options off the table concerning anything to do with military force."

Testifying before the committee for the first time since February, Rice sought to reassure jittery members of Congress that the Bush administration had a plan for success: helping Iraqis clear out insurgents and build durable, national institutions.

She told lawmakers the United States will follow a model that was successful in Afghanistan. Starting next month, she said, joint diplomatic-military groups-- Provincial Reconstruction Teams-- will work alongside Iraqis as they train police, set up courts, and help local governments establish essential services.

But even as Rice tried to crystalize the plan, Republicans and Democrats asked her pointed questions they say Americans need to know.

"I'm not looking for a date to get out of Iraq," Sen. Joseph Biden of Delaware, the top Democrat on the panel, said. "But at what point, assuming the strategy works, do you think we'll be able to see some sign of bringing some American forces home?"

Rice declined to answer directly, choosing to leave an estimate to military commanders. "I don't want to hazard what I think would be a guess, even if it were an assessment, of when that might be possible," Rice said.

Later, Sen. Paul Sarbanes, D-Md., told Rice that her response to questions about U.S. troop withdrawal "leads me to draw the conclusion that you're leaving open the possibility that 10 years from now we will still have military forces in Iraq."

"Senator, I don't know how to speculate about what will happen 10 years from now, but I do believe that we are moving on a course on which Iraqi security forces are rather rapidly able to take care of their own security concerns," Rice responded.

Republican Sens. Chuck Hagel of Nebraska and Lincoln Chafee of Rhode Island were among several lawmakers who asked Rice whether the Bush administration was considering military action against Iran and Syria, and asked whether the president would circumvent congressional authorization if the White House chose that option.

"I will not say anything that constrains his authority as commander in chief," Rice said.

The lawmakers' queries followed Rice's earlier remarks that: "Syria and, indeed, Iran must decide whether they wish to side with the cause of war or with the cause of peace."

As Rice spoke, a woman in the second row of spectators shouted "Stop the killing in Iraq." A police officer motioned her out of the room.

By State Department design, Rice testified before the committee just days after Iraq apparently approved its first constitution since a U.S.-led coalition ousted Iraqi dictator Saddam Hussein in 2003. Her appearance also coincided with the start of Saddam's trial in Baghdad for a massacre of 150 of his fellow Iraqis.

At the White House, press secretary Scott McClellan praised Saddam's trial as "a symbol that the rule of law is returning to Iraq."

Rice heralded the referendum on the charter as "a landmark" and said the US. strategy was moving from a stage of transition to a stage of preparing a permanent Iraqi government.

"Clear areas from insurgent control, to hold them securely, and to build durable, national Iraqi institutions," Rice said

"Our strategy is to clear, hold, and build," she said. "The enemy's strategy is to infect, terrorize, and pull down."

Alongside Iraqi allies, she said, the United States is working to dismantle the insurgent network and disrupt foreign support for them, maintain security in areas insurgents no longer hold, and build national institutions to "sustain security forces, bring rule of law, visibly deliver essential services, and offer the Iraqi people hope for a better economic future."

With President Bush's poll numbers dragged down by public discomfort over Iraq, Rice was seeking to reassure lawmakers-- who are feeling the heat from their war-weary constituents-- that U.S. policies toward Iraq are sound.

Republicans and Democrats on Capitol Hill are raising questions about the Bush administration's diplomatic and military plans in Iraq amid a rising U.S. death toll, soaring costs and slumping public support for the war.

Saturday's vote was a political milestone on Iraq's path to forming a legitimate democratic government. Efforts by skeptical Sunni Arabs to defeat the charter appear to have failed, but the Bush administration has embraced their unexpectedly large turnout at the polls as a sign democracy is taking root.

The next step is in December, when Iraqis elect a new parliament and a new government-- the first permanent, constitutional government since Saddam's regime ended.