But the White House also affirmed that it has no plan to reassess its strategy in the war-ravaged country, despite a surge in US casualties there and unrelenting sectarian bloodshed.
Bush was asked in an ABC News interview late Wednesday if he agreed with a New York Times columnist's comparison of the strife in Iraq with the Tet Offensive, which is considered a key turning point in the US war in Vietnam.
"He could be right," Bush said. "There's certainly a stepped-up level of violence."
Bush said insurgents were trying "to inflict enough damage that we'd leave."
"First of all, al Qaeda is still very active in Iraq. They are dangerous. They are lethal. They are trying to not only kill American troops, but they're trying to foment sectarian violence," he said.
"They believe that if they can create enough chaos, the American people will grow sick and tired of the Iraqi effort and will cause (the) government to withdraw," Bush said.
The Tet Offensive, a campaign launched by the North Vietnamese in early 1968, was considered a military defeat for them, but the scope of the assault shocked Americans and helped turn US public opinion against the war.
Many Americans concluded that the war was unwinnable or victory too costly.
The White House later sought to put the comparison in context.
"The full context was that the comparison was about the propaganda waged in the Tet Offensive ... and the president was reiterating something he's said before -- that the enemy is trying to shake our will," Dana Perino, a Bush spokeswoman, said in a statement.
"They know that we're a caring and compassionate people and that we're deeply affected by gross violence," she said.
"The president also believes the American people understand the importance of beating our enemy who is determined to kill innocent freedom-loving people."
The comments came amid a steep spike in US deaths in Iraq, including 10 killed in a single day, on Wednesday.
The US military announced two more US soldier deaths early Thursday, bringing the total number of American fatalities in Iraq this month to 69.
The US administration said the surge in US casualties would not lead to a reassessment of the US strategy there.
"The strategy is to win," spokesman Tony Snow said in the southern state of North Carolina Wednesday. "As everybody says, correctly, we've got to win. And that comes at a cost."
"The president understands not only the difficulty of it, but he grieves for the people who have served and served with valor," said Snow, who told reporters that US forces "do believe in the mission."
Also on Thursday, a suicide truck bomber slammed into an Iraqi police station in the northern city of Mosul, killing 10 and wounding 14, police said. Nine of the dead were civilians.
The attacks came amid a spectacular surge in insurgent and sectarian violence around Iraq, which has claimed hundreds of lives since the start of the Islamic holy month of Ramazan just over three weeks ago.
In the television interview, the US leader expressed support for Iraqi Prime Minister Nuri al-Maliki but warned that his patience is not infinite.
"In my judgement, Maliki has got what it takes to lead a unity government," Bush said.
"I'm patient. I'm not patient forever. And I'm not patient with dawdling. But I recognise the degree of difficulty of the task, and therefore, say to the American people, we won't cut and run," he said.
Bush ruled out a complete troop withdrawal as long as he is president, through January 2009.
However, a high-powered panel named by the US Congress to assess policy options in Iraq is weighing recommendations that could deal a blow to Bush's "stay-the-course" policy in Iraq.
A source associated with the Iraq Study Group confirmed media reports that options under consideration include a phased withdrawal of US soldiers from Iraq and an opening of diplomatic channels with Iran and Syria.
Both steps would represent a major break with the president's policies. The 10-member panel of bipartisan heavyweights will deliver its report sometime after the November 7 mid-term elections, according to its leader, respected former secretary of state James Baker.

Copyright AFP (Agence France-Presse), 2006