The long-awaited report to Congress next week by General David Petraeus and Ambassador Ryan Crocker on the progress of the military surge in Iraq will offer few surprises. But it will offer an opportunity for Senator McCain to recover lost ground in the Republican presidential race.

Alone among his fellow candidates, the Arizona lawmaker was quick to jump to President Bush’s side when, in the wake of the midterm elections last November in which the Republicans lost support all around, the administration doubled down and provided General Petraeus with extra troops to bring order to Iraq.

The idea of the surge coincided with Mr. McCain’s long-held view that the 2003 invasion of Iraq had taken place with too few ground troops. A constant critic of the administration’s previous war strategy and one of the few senior Republicans to propose the removal of Defense Secretary Rumsfeld, Mr. McCain confirmed his status as the GOP’s favorite maverick by energetically endorsing the president’s new surge policy.

While others began to redefine their attitudes toward the war and advocate early withdrawal, Mr. McCain’s decision to back the president’s revised war plan wholeheartedly was considered risky. The cost to his presidential campaign has been high, though the senator has said he believes that his dip in support, and the loss both of funding and his front-runner status, has had more to do with his promotion, again alongside Mr. Bush, of the failed immigration reforms.

Few have been as eloquent, mature, and persuasive in approaching worldwide Islamist violence as the senior senator from Arizona. In a keynote speech in April, Mr. McCain spelled out the stark option facing Congress and the American people.

“We now confront a choice as historically important as any we have faced in a long while,” he told cadets at the Virginia Military Institute. “Will this nation’s elected leaders make the politically hard but strategically vital decision to give General Petraeus our full support and do what is necessary to succeed in Iraq? Or will we decide to take advantage of the public’s frustration, accept defeat, and hope that whatever the cost to our security, the politics of defeat will work out better for us than our opponents? For my part, I would rather lose a campaign than a war.”

It is clear from General Petraeus’s remarks in Baghdad this week that the top commander of American forces in Iraq will tell Congress that his surge strategy has achieved considerable progress in reducing violence and lawlessness in Iraq. The general also is expected to announce that, depending on conditions on the ground, American troops in Iraq will start returning home in March.

The announcement will alter the political climate in Washington, bolstering the president’s flagging fortunes and causing the Democratic leadership to re-evaluate their plans to withhold funding for the war.

The sunny view of the Iraq occupation painted by the general and the ambassador to Baghdad also offers Mr. McCain a rare chance to revitalize his faltering presidential campaign. His judgment on the war has been proved to be right, while those who bowed so readily to anti-war public opinion can be portrayed as callow, opportunistic, and reckless.

At Wednesday night’s Fox News Republican debate in New Hampshire, Mr. McCain set out to alter his fortunes, pressing the point that his backing of the surge represents a more considered understanding of world events than that of his rivals. “I’ve spent my life in national security issues,” he said. “I’ve taken unpopular stances because I knew what was right.”

While acknowledging that opponents tried to pin his name to the surge, he took credit for believing from the beginning that the plan was the right course. “I advocated very strongly the new strategy that some Democrats have called the McCain strategy — which it is not,” he said. “And I believe that this strategy is winning. I know the conflict. I know war. I have seen war. I know how the military works. I know how the government works. I understand national security.”

Mr. McCain also gave notice that he would be prominent in the Senate debate on the surge. “The great debate is not whether [the surge is] apparently working or not. The great debate is going to take place on the floor of the United States Senate the middle of this month. And it’s going to be whether we set a date for withdrawal, which will be a date for surrender, or whether we will let this surge continue and succeed.”

One element of Mr. McCain’s campaign remains elusive: winning an open endorsement, or even an encouraging word, from Mr. Bush. No candidate has been as devoted to the president’s policies on the war and immigration than Mr. McCain, often to his detriment, and the senator has repeatedly boosted the president’s views on the stump.

If Mr. Bush were to suggest next week that the senator deserved praise for supporting him when the going was tough, he would offer Mr. McCain the lifeline he so desperately needs.