WASHINGTON — The Iraqi government has not yet fully met any of 18 goals for political, military and economic reform, the Bush administration said Thursday in an interim report certain to inflame debate in Congress over growing calls for a American troop withdrawal.

In an assessment required by Congress, the administration accused Syria of fostering a network that supplies as many as 50 to 80 suicide bombers per month for Al Qaeda in Iraq. It also said Iran continues to fund extremist groups.

The report said that despite progress on some fronts by the government of Nouri al-Maliki, “the security situation in Iraq remains complex and extremely challenging,” the “economic picture is uneven” and political reconciliation is lagging.

At a news conference that coincided with the report’s release, President Bush said, “I believe we should succeed in Iraq and I know we must.”

The report warned of “tough fighting” during the summer, as American and Iraqi forces “seek to seize the initiative from early gains and shape conditions of longer-term stabilization.”

While President Bush announced last winter he was ordering thousands of additional troops to the war zone, the full complement has only arrived in recent weeks. “The full surge in this respect has only just begun,” the report said.

In an evident jab at critics of Mr. Bush’s war policies, the report also said progress toward political reconciliation was hampered by “increasing concern among Iraqi political leaders that the United States may not have a long term-commitment to Iraq.”

The report was issued in the fifth year of a war that has taken the lives of more than 3,000 American troops, and is costing America an estimated $10 billion a month.

In all, it credited the Iraqi government with satisfactory progress on eight benchmarks, unsatisfactory progress on another eight and mixed results on the other two.

At the White House, the press secretary, Tony Snow, said the fact that “satisfactory progress” has been made in several security areas “should provide some space for the government of Iraq to make progress on key political benchmarks.”

“The report is balanced and sober,” he said in a statement. “It documents the challenges faced by U.S. and Iraqi forces and provides a basis for measuring progress as the surge enters the stage of full implementation.”

The report was designed as an interim assessment of the shift in policy that Mr. Bush announced last winter, in the wake of Republican defections in an election in which the war played a significant role.

A second report is due in September from the commander of U.S. forces in Iraq, General David Petraeus.

The new assessment landed as both houses of Congress debated legislation to order the withdrawal of American troops by next spring. The House appeared on track to approve its version of the bill later in the day, but opponents in the Senate appear to have the strength to prevent a final vote next week in the Senate.

In either event, Mr. Bush has pledged to veto the legislation, and has enough support to make his rejection stick.

Still, with polls showing scant public support for the war, and the American casualty count climbing, Republicans whose names will be on the 2008 election ballot have shown increasing signs of restiveness in recent weeks.

Several veteran Republicans have called on Mr. Bush to change course, and Senator Smith, Republican of Oregon, on Wedneday became the first member of his party to announce on the Senate floor that he will support legislation that orders a troop withdrawal to begin within 120 days, to be completed by next April 30.

That announcement, along with other calls for a dramatic change in policy, prompted an acerbic response from Rep. John Boehner, Republican of Ohio. “Wimps,” he called fellow GOP lawmakers who part company with the president on the war.

Mr. Bush in recent days rejected calls for any shift in strategy before September.

But neither he nor administration officials have speculated about what might happen after that.

The administration’s report, however, referred repeatedly to the Iraq Study Group that issued a report last winter that drew widespread praise in Congress.

The bipartisan panel said Mr. Bush should start handing off the combat mission to the Iraqi forces and pave the way for a drawdown of American forces in 2008.

“While all of those conditions have not yet been met, and the new strategy is still in its early stages, there are some encouraging signs that should, over time, point the way to a more normalized and sustainable level of U.S. engagement in Iraq, with a decreasing number of U.S. combat forces increasingly focused on a core set of missions, such as those set out by the bipartisan Iraq Study Group,” the report states.