Less than three weeks before U.S. congressional elections, Democrats are enthusiastic about their chances, while Republicans are in a defensive mode, hoping to limit Democratic gains.

US Capitol, Washington DC

A new public-opinion poll conducted by NBC News and the Wall Street Journal highlights the political challenges that lie ahead for the Republicans.

Only 16 percent of voters in the survey approved of the job the Republican-led Congress is doing.  That is the lowest approval rating for Congress since 1992.

The same poll also found that voters preferred the Democrats to be in control of Congress by a margin of 52 percent to 37 percent.

Democrats, like Maryland Congressman Chris Van Hollen, believe public discontent over the Iraq war is a major factor in this year's election.

"They see that we have not completed the job against Osama bin Laden and al-Qaida in Afghanistan," he said.  "They see that we took our eye off the ball there and went into Iraq.  And they see that what we have in Iraq is a mess and chaos and the result of many, many things, including gross incompetence by the Bush administration."

All 435 seats in the House of Representatives are at stake this year, as well as 33 seats in the 100-member Senate and 36 state governorships.

Democrats need to gain 15 House seats to retake control of that chamber and six additional seats to recapture control of the Senate.

Republicans are trying to shift the focus of the election debate away from Iraq to national security concerns like terrorism and economic issues like taxes.

Republicans also insist the House races will be determined more by local issues and personalities, not national trends.

Rep. Tom Reynolds speaks at a fundraiser in Amherst, NY, Oct. 4, 2006

New York Congressman Tom Reynolds is leading the Republican effort to maintain a majority in the House of Representatives.

"We are dealing with fierce contests, fought by local personalities on local, pocketbook issues," he said.  "The old saying still rings true, voters may hate Congress, but they like their congressman."

Most congressional elections are fought more over local issues.  But public opinion surveys have for months suggested that Republicans face a negative public mood as Election Day approaches.

"National polling and polls in individual [congressional] districts are very clear," said Stuart Rothenberg, who publishes a non-partisan political newsletter in Washington.  "Voters are dissatisfied with the direction of the country, they are dissatisfied with the performance of their political leaders, including the president, and certainly including Congress.  They are pessimistic."

Experts say much of the bad mood is directly traceable to the difficulties in Iraq.

"And at this point, I think, Iraq is even making us pessimistic about the American economy," said Karlyn Bowman, who monitors public opinion at the American Enterprise Institute in Washington. "So, it is Iraq, Iraq, Iraq, I think, probably number one, two and three [in priority], with everything else falling in a pretty distant second place."

Rep. Mark Foley (file photo)

In addition to Iraq, Republicans are also concerned about the recent scandal involving former Republican Congressman Mark Foley and the sexually suggestive e-mails he sent to young male pages who worked in Congress.

Republicans worry the Foley scandal could hurt their efforts to encourage Christian conservatives to vote on November 7.

Democrats are growing increasingly confident about their prospects of winning the House and possibly the Senate.  Democratic control of even one chamber of Congress would have a major impact on the balance of power in Washington.

"And everybody in Washington believes that, if the Democrats take control of one or both chambers [of Congress], there will be a lot of investigations about the administration," said analyst Stuart Rothenberg.  "And not just Iraq, but also the response to Hurricane Katrina last year, health care, prescription drugs, gas prices."

President Bush's top political adviser, Karl Rove, told The Washington Times newspaper that he remains confident Republicans will prevail in the elections, in part because they have been better than Democrats at mobilizing their core supporters to vote in recent elections.