Iraqi Prime Minister Ayad Allawi will address a joint session of Congress and make high-profile appearances in Washington next week, a debut visit to the United States that the Bush administration will make the centerpiece of a vigorous election-year defense of its troubled Iraq policy, according to U.S. officials.

The visit by Iraq's charismatic interim leader, who will also speak to the U.N. General Assembly and be part of a sustained media effort, could provide a boost to President Bush's campaign by reframing the controversial U.S. intervention in Iraq in terms of accomplishments rather than problems, U.S. officials said. Allawi is expected to emphasize the transformation of Iraq since the ouster of Saddam Hussein, to thank the United States on behalf of the Iraqi people and to appeal for ongoing support to complete the job, they said.

At the opening session of the U.N. General Assembly, Allawi intends to call for an end to the divisions over Iraq at the world body and appeal for greater international support for Iraq as it goes through three elections and writes a new constitution over the next 16 months, U.S. officials said. The new government wants a larger U.N. presence to facilitate the crucial votes and help with providing security for the U.N. staff, which had been targeted by insurgents in the past.

The Allawi visit comes amid growing public concern about the escalating insurgency in Iraq and mounting congressional criticism from both Republicans and Democrats over the year-long delay in getting $18 billion into reconstruction projects, which are pivotal in countering anti-American sentiment and a key to reviving Iraq.

In particularly harsh criticism, Senate Foreign Relations Committee Chairman Richard G. Lugar (R-Ind.), at a hearing yesterday on Iraq reconstruction spending, assailed some U.S. officials -- the "dancing-in-the-street crowd," he called them -- for misrepresenting the problems with American strategy in Iraq. Sen. Joseph R. Biden Jr. (D-Del.) condemned the "disconnect" between descriptions from U.S. officials and "the reality on the ground."

Foreign policy analysts also now warn that the United States and Iraq are reaching a critical moment in efforts to turn the tide of both the insurgency and public perceptions. "Our whole problem in Iraq is that we consistently underestimated the challenge," said Bruce Hoffman, a counterterrorism expert and director of Rand Corp.'s Washington office. With recent political and military changes, he said, "we're getting it. But we've always been behind the curve."

Indeed, some U.S. officials predict that insurgents' attacks are likely to intensify as they attempt to influence the U.S. election in November and then to undermine Iraq's first poll for a national assembly in January. "We expect increasing violence as we get towards the January election, and frankly I would not be surprised if some of that violence was directed against our own election on November 2," Deputy Secretary of State Richard L. Armitage said yesterday in Prague.

Even so, on the eve of Allawi's visit, the administration is trying to paint a positive picture of what has been achieved since the June 28 handover of political power from the U.S.-led coalition to an interim government selected by U.N. and U.S. envoys. U.S. officials depict the transfer as having gone better and faster than anticipated, with Allawi taking firm control and the new U.S. Embassy moving into a support position. And while the media is focusing on the recent upsurge in violence, they say, much of Iraq is quiet.

Since the cease-fire last month in the Shiite holy city of Najaf, they add, the Mahdi Army of rebel cleric Moqtada Sadr has been dispersed and Sadr has gone underground, removing the most sensitive security challenges. They also point out that, in the volatile Sunni triangle north of Baghdad, U.S. troops are now able to move in and out of the city of Samarra without getting fired on and that only about 100 insurgents are believed left in the city after the majority fled.

But military experts say the insurgency appears to have intensified since the turnover. More than 1,000 U.S. troops were wounded in August, and more U.S. troops have been killed since the turnover of power in late June than were killed during the 2003 invasion of Iraq. An increasing number of U.S. troops are being hit by gunfire or suicide bombers, rather than by indirect means such as mortar fire and roadside bombs, indicating that insurgents are now willing and able to confront U.S. forces directly in more sophisticated and coordinated attacks, military analysts say.

Also, it isn't clear whether insurgents in Samarra have been forced out or have simply beaten a tactical retreat in order to return at a time of their choosing, some officials and analysts caution, adding that Sadr's army may also be waiting for the right time to strike again.

There also are fears among security experts that insurgents will soon begin targeting poll workers and others who are essential to holding elections, just as police officers and others who work with U.S. forces have been targeted for months.

The U.S. strategy in Iraq is "extremely unrealistic," Francis Fukuyama, a foreign policy expert, said at a symposium on Iraq at Johns Hopkins University on Tuesday. He was especially critical of the plan to rely increasingly on Iraqi security forces and to hold nationwide elections in just a few months. "I think that anybody who believes they are going to be able to execute this plan is living in a total fantasyland," he said.