But Eric Ruff, the Pentagon press secretary, stopped short of saying that al-Qaeda wanted a Democratic victory in the November 7 poll and denied emphatically that he was implying that.
He singled out a Washington Post report quoting a local al-Qaeda leader as saying the group's leader, Abu Ayyub al-Masri, wanted redoubled attacks "to have a great effect on the American elections."
"It would seem that if they can increase the violence, they can increase opposition to the war and have an influence against the president," Mr Ruff told reporters.
Escalating sectarian and insurgent violence in Iraq and the seeming inability of Iraqi and US forces to check it have fuelled criticism here that the administration's Iraq strategy is not working.
The military Friday reported the death of the 97th US service member this month in Iraq, making October the deadliest month for the US military in a year.
The monthly toll is approaching all-time highs reached in 2004 during major battles for Fallujah and control of the Shi'ite south.
Mr Ruff said there were other explanations for the spike in violence, including heightened insurgent activity during the Muslim holy month of Ramadan and stepped-up US military operations in Baghdad.
But he cast the struggle as a "battle for the hearts and minds of the American people."
He said Iraqi insurgents "know this is a battle for the resolve of the American people. And if they can influence elections and get the American people to get tired of this war through their attacks,
I think they see something."
Polls show plummeting public support in the United States for the war and low approval of Bush's performance.