The assessment would come at a critical time in both American and Iraqi politics. U.S. voters will be deciding between a Republican candidate committed to keeping troops in Iraq as long as Petraeus and other ground commanders say is necessary, and a Democratic challenger who supports the immediate withdrawal of forces.
At the same time, Iraq will be headed into its much-anticipated provincial elections, which U.S. officials have described as a crucial step in building national reconciliation by increasing participation by the Sunni minority.
Petraeus said conditions on the ground will still dictate his decision. But by September, when he is slated to assume control of U.S. Central Command, "my sense is that I will be able to make a recommendation at that time for some further reductions," he said.
Petraeus cautioned that he was not implying that that means a particular brigade or major combat formation. "But I do believe there will be certain assets that, as we are already looking at the picture right now, we'll be able to recommend can be either redeployed or not deployed to the theater in the fall," he said.
President George W. Bush said he looked forward to hearing what his generals would recommend, and he did not tip his hand as to what he wants to hear.
"My message to our commanders is you will have all the troops, you will have all the resources you need to win in Iraq," Bush said from Fort Bragg, North Carolina, where he was speaking to 17,000 paratroopers from the Army's 82nd Airborne Division.
Also on Thursday, the Senate voted 70-26 to approve $165 billion to pay for military operations in Iraq and Afghanistan into next spring, when Bush's successor will set war policy. All told, the measure contains $212 billion over the coming two years, plus about $50 billion more through 2017 for veterans education benefits.
In recent months, Petraeus has helped to tame growing opposition to the war in Congress by providing measured assessments of progress and warning that an exodus of U.S. troops would result in chaos.
His unflappable style was on display again Thursday in a Senate Armed Services Committee hearing to confirm him for the Central Command post. Its area of responsibility includes Iraq, Iran, Lebanon Pakistan, parts of Africa and Afghanistan. The hearing was considerably less contentious than his past congressional appearances and even came with an endorsement by the panel's chairman, Sen. Carl Levin, and Democratic presidential hopeful Hillary Rodham Clinton.
Also receiving a warm reception was Lt. Gen. Raymond Odierno, expected to replace Petraeus as the top commander in Iraq. Odierno previously served 15 months in Iraq as Petraeus' deputy.
"Regardless how long the administration may choose to remain engaged in the strife in that country, our troops are better off with the leadership these two distinguished soldiers provide," said Levin, a Democrat.
Petraeus has previously been reluctant to say when his next assessment of troop levels might be. Earlier this year he recommended - and Bush agreed - to withdraw by July the 30,000 extra troops sent to Iraq last year as part of a major security push to blunt increasing sectarian violence.
In testimony last month, Petraeus said he needed a 45-day period of evaluation and then an indefinite period of assessment before he would recommend any further pullouts, holding his ground against Democrats demanding to know whether more withdrawals were possible before Bush leaves office in January.
Levin said Petraeus' pledge to review troop levels by September was "good news to most of us."
On a less-optimistic note, Petraeus said it is unlikely that Iraqi security forces will take the lead in all provinces this year, as was recently predicted by the Defense Department. Petraeus said events in the past month and a half - an allusion to the spike in violence in Basra - have pushed that goal to 2009.