"Iraq has become the central issue of the midterm elections," said researchers with the Pew Research Centre, in a statement that accompanied the survey.
"There is more dismay about how the US military effort in Iraq is going than at any point since the war began more than three years ago," the statement read.
The comprehensive poll of 1,800 respondents sampled voter opinions on a broad range of top issues, from immigration, to the war in Iraq, to the falling price of energy.
The poll found that 58 percent of the US public believes the US military effort in Iraq is not going well, 47 percent say the war is hurting, not helping, the fight against terrorism.
Sex scandal dismissed
The survey also found that when it came to voting, Americans were remarkably unaffected by the handling of lurid sexual messages sent by former Republican lawmaker Mark Foley to teenage pages in Congress.
The Pew Centre found that Democrats had a 51 percent to 38 percent advantage over Republicans before last week's scandal broke, and 50 percent to 37 percent edge afterward.
Among voters who said national issues were of paramount importance for them, about half -- 51 percent -- cited the deteriorating situation in Iraq as the most important concern.
Terrorism came in second place at 37 percent while 35 of respondents cited the economy.
Another important recent development -- the drop in the price of gasoline-- also appeared not to have impacted voter feelings greatly.
The survey showed that while most respondents were aware of the recent fall in gas prices, they were also likely to complain about a faltering US economy.
The poll put US President George W. Bush's job approval rating at 37 percent, with 63 percent of respondents saying they are dissatisfied with the way things are going in the country.
As with earlier Pew surveys, an unusually high percentage of voters – 39 percent -- envision their ballot as a vote "against" Bush rather than for him.
The survey found the current climate to be particularly treacherous for incumbents, with 27 percent of voters saying they do not want to see their own representative win re-election, down from 32 percent in June.
But anti-incumbent feeling seemed less pronounced than in the historic 1994 midterm elections, when voters ousted Democrats from the leadership of the House of Representatives, the Pew researchers noted.