Campaign strategists for President Bush and Senator Kerry of Massachusetts struggled yesterday to divine the state of the presidential race as two new polls showed the candidates neck-and neck while a third showed the president with a commanding 13-point lead.

A Harris Poll and a survey for a Washington think tank, the Pew Center, indicated that the much-vaunted bounce Mr. Bush received from the Republican National Convention has evaporated. Some of the data showed a clear trend in Mr. Kerry’s favor.

However, a Gallup Poll set for release tomorrow shows 55% of likely voters backing Mr. Bush and 42% for Mr. Kerry, according to the Associated Press.

“This polling stuff is going to keep us with agita for the rest of the election,” said a political science professor at Baruch College, Douglas Muzzio.

The conflicting numbers emerged as the Democratic candidate used tough rhetoric to accuse Mr. Bush of deceiving Americans about the gravity of the challenges in Iraq.

In a speech to a National Guard Association conference in Las Vegas, Mr. Kerry claimed that Mr. Bush’s address to the same group on Tuesday demonstrated that the president was caught up in “a fantasy world of spin.”

“He failed to tell you the truth. You deserve better. The commander in chief has to level with the troops and the nation,” Mr. Kerry said. “The president stood right here where I’m standing and he didn’t acknowledge that more than 1,000 men and women have lost their lives in Iraq.” “He did not tell you that with each passing day we’re seeing chaos, more violence, more indiscriminate killings.”

Mr. Kerry also picked up on press accounts that American intelligence agencies recently gave the White House a gloomy assessment of the situation on the ground. “His own intelligence officials have warned him for weeks that the mission in Iraq is in serious trouble,” Mr. Kerry said. “As president I will always be straight with you, on the good days and the bad days,” he vowed.

Mr. Kerry received a polite but rather muted reception from the guard members, many of whom cheered Mr. Bush’s address earlier in the week.

During a bus trip across Minnesota, Mr. Bush argued that Mr. Kerry’s views on Iraq have been dangerously erratic. The president also veered close to Vice President Cheney’s controversial statement that the election of Mr. Kerry could precipitate a terrorist attack.

“The fellow I’m running against has probably had about eight positions on Iraq. For the war but wouldn’t provide the funding. Then, he was the anti-war candidate. Then, he said, knowing everything we know today, I’d have done the same thing. Then he said we’re spending too much money, that’s after he said we weren’t spending enough money,” Mr. Bush said at a campaign stop in St. Cloud, Minn. “Let me be clear: Mixed signals are the wrong signals to send to our troops in the field, the Iraqi people, to our allies, and, most of all, to our enemies,” the president said.

At a rally in Albuquerque, Vice President Cheney derided Mr. Kerry’s comments on Iraq during an interview Wednesday with radio host Don Imus.

“He was absolutely incoherent,” Mr. Cheney said of Mr. Kerry. “I’ve never seen a candidate with as many different positions on one issue.”

Mr. Kerry’s aides contend that his position on Iraq has remained consistent. The vice president, however, pointed out after the interview that even Mr. Imus, who is a Kerry supporter, said he couldn’t makes heads or tails of the senator’s comments. “I was just back in my office banging my head on the jukebox,” Mr. Imus told his listeners. “I don’t know what he’s talking about.”

Despite the uncertainty about Mr. Kerry’s views, it became abundantly clear yesterday that Democrats see the situation in Iraq as a political liability for the president.

The Democratic National Committee and the left-leaning MoveOn.org each unveiled new television ads that describe the president’s Iraq policy as both disastrous and directionless.

For the first time, the Democratic Party is using actual images from the Iraq war in a campaign advertisement. The new ad shows a clip from Mr. Bush’s May 2003 speech beneath a “Mission Accomplished” banner. That is followed by a series of still photos of unrest in Iraq, including an image of a soldier who appears to be hanging his head in despair.

The ad notes that 867 American soldiers have been killed in Iraq since Mr. Bush’s speech. The remainder of the ad criticizes Mr. Bush’s economic record, before concluding, “America can do better.” Party officials said they were purchasing almost $7 million of airtime for the ad, which will appear initially on cable news channels and in 11 battleground states.

While Mr. Kerry stopped just short yesterday of charging that Mr. Bush lied about the conditions in Iraq, the Democratic Party chairman, Terence McAuliffe, showed no such compunction.

“I’m just aghast and shocked that the president of the United States would go before the National Guard, absolutely lie to the national guardsmen and say that things are getting better in Iraq, when his own intelligence briefing has a report that things aren’t going to get better,” Mr. McAuliffe said during a conference call to announce the new ad.

The Moveon.org television advertisement shows an arresting image of an American soldier sinking in quicksand. The announcer refers to a “growing insurgency” in Iraq and says that Mr. Bush “has no real plan to end the war.” As the “soldier” struggles and hoists his weapon above his head, the narrator declares, “George Bush got us into this quagmire. It will take a new president to get us out.”

The group said it would spend $260,000 to air the ad in five television markets and on CNN.

The Bush campaign immediately condemned the MoveOn.org spot and called on Mr. Kerry to repudiate it.

In a statement issued by the president’s campaign, a former Senate majority leader, Robert Dole, said the ad went too far by portraying “a defeated American soldier.”

“It’s one thing to debate whether we should take the fight to the terrorists, but depicting an American soldier in effect surrendering in the battle against the terrorists is beyond the pale,” Mr. Dole said.

Mr. Dole said Mr. Kerry’s statements questioning the ability of American troops to maintain order in Iraq and his description of the coalition as “window dressing” harken back to comments Mr. Kerry made after returning from his Navy service in Vietnam.

“This is all reminiscent of his appearance before a Senate committee in 1971 where he suggested, with nothing but second-hand information, that American GIs were committing atrocities and war crimes of the worst kind in Vietnam,” Mr. Dole said.

Analysts said the new poll numbers suggest that any lead Mr. Bush enjoyed in early September may be disappearing.

“It’s real, real close,” Mr. Muzzio said. “You got a little bit of a bubble and that bubble has eroded.”

Mr. Muzzio said he believes that news reports of turmoil in Iraq took the shine off of the convention.

“The news generally has not been favorable to Bush. Reality has set in,” he said. “Iraq is worse than Kerry is.”

The Harris Poll out yesterday found Mr. Kerry with 48% support and Mr. Bush with 47% among 803 voters that pollsters consider likely to turn out in November. Mr. Nader registered just 2% support in the poll, which was taken from September 9 to 13.A slight majority, 51%, of the likely voters said Mr. Bush did not deserve re-election.

The survey conducted by the Pew Research Center for the People and the Press had Mr. Bush ahead by a point among likely voters. The president had 47%, as compared to 46% for Mr. Kerry. The group’s polling showed a clear trend, with Mr. Bush ahead of Mr. Kerry by as much as 16% last week and the two men essentially even earlier this week.

A survey for Investor’s Business Daily taken by TechnoMetrica and released on Tuesday showed Mr. Bush and Mr. Kerry tied among likely voters.

The Gallup poll of 767 likely voters was taken September 13 to 15.