For President Bush's new plan for Iraq, the clock is already ticking. It appears to face time pressure on at least two fronts.
On Capitol Hill, the patience of the Democratic-controlled Congress for the proposal to dispatch 21,500 more US troops to the country is clearly limited. It's possible that the antipathy of many lawmakers towards the plan could foreshadow a resolution of disapproval - or even attempts to limit funds for the war.
In Iraq, the government of Prime Minister Nouri al-Maliki is supposed to move new Iraqi forces into Baghdad within weeks. If these Iraqi units don't materialize, the US may be forced to reevaluate its strategy, according to administration officials.
Thus by early next month the political and military context for the US troop buildup could look very different than it does today. It is even possible that the White House could stop the surge of increased US forces before it gets fully under way.
"I think we're going to know fairly early in this process whether the Iraqis are in fact prepared to fulfill the commitments they've made to us," said Secretary of Defense Robert Gates at a Senate Armed Services Committee hearing on Friday.
This is not to say that the White House is hedging on its strategy. Administration witnesses defended it vigorously in congressional testimony following President Bush's Wednesday speech to the nation.
"After a lot of thought and after looking at a lot of different options, the president very much decided that this is the best option for us going forward," said Secretary of State Condoleezza Rice in a Thursday appearance before the House Foreign Affairs Committee.
But the White House appeared somewhat taken aback by the vehemence of congressional reaction to the plan, which would raise US troop levels in Iraq by 21,500, while calling on the Iraqi government to increase its own forces in Baghdad and do more to quell sectarian violence.
For the administration, the nadir in Washington was perhaps Thursday's hearing of the Senate Foreign Relations Committee, a panel that includes at least seven lawmakers who have contemplated running for president themselves. Secretary of State Rice was hammered by committee members, Republicans as well as Democrats.
Sen. Chuck Hagel (R) of Nebraska went so far as to say that the president's new plan "represents the most dangerous foreign policy blunder in this country since Vietnam."
Democratic leaders say they intend within a few weeks to hold votes in both House and Senate on symbolic resolutions of disapproval of the Bush's strategy. Though nonbinding, such votes could be difficult ones for many Republicans, considering the extent of public disapproval of the Iraqi situation.
Whether Democrats would go further, and try to curb funding for the troop increase, remains unclear. Some party leaders, such as Sen. Joseph Biden (D) of Delaware, have cast doubt on the constitutional powers of Congress in this regard. But Senate Minority Leader Mitch McConnell has charged that this is what Democrats really want to do - and has vowed to try to block votes critical of administration policies.
"Congress is completely incapable of dictating the tactics of the war," Senator McConnell said this week.
The bigger influence on the course of the US troop buildup in Iraq, however, may be the Iraqis themselves.
Administration officials this week were careful to note that the Iraqis have specific tasks to accomplish within a short period of time. One new Iraqi brigade should be moved to Baghdad by Feb. 1, noted Secretary of Defense Gates before the Senate Armed Services Committee. Another should be in place two weeks later.
"The premise of this entire strategy is the Iraqis taking the lead and fulfilling those commitments," he said.
The Iraqis seem eager to take control of the security situation, and the US has received commitments of support from officials throughout the Iraqi government, not just Prime Minister Maliki, said Gates.
But the new defense chief readily admitted that the Iraqi government has made such promises before, and they have come to naught. "Their record of fulfilling promises is not an encouraging one," he said.
Administration officials did not directly say they would put the brakes on the troop buildup if the Iraqis do not move as intended. But they did say that such a situation would case a reevaluation of US strategy.
"Before we have sent in very many additional troops we will have a pretty good idea, at least on the military side, as to whether the Iraqis have stepped up to the plate to fulfill their commitments," said Gates.
On the other hand, if all works as planned and the new deployments tamp down Iraqi violence, a US drawdown might follow later this year, according to Gates.
Meanwhile, support for President Bush's policies continues to hover near record lows. An AP-Ipsos poll found 68 percent of respondents disapproving of Bush's handling of Iraq.