WASHINGTON, Nov. 1 — A substantial majority of Americans expect Democrats to reduce or end American military involvement in Iraq if they win control of Congress next Tuesday and say Republicans will maintain or increase troop levels to try to win the war if they hold on to power on Capitol Hill, according to the final New York Times/CBS News poll before the midterm election.

The poll showed that 29 percent of Americans approve of the way President Bush is managing the war, matching the lowest mark of his presidency. Nearly 70 percent said Mr. Bush did not have a plan to end the war, and 80 percent said Mr. Bush's latest effort to rally public support for the conflict amounted to a change in language but not policy.

The poll underlined the extent to which the war has framed the midterm elections. Americans cited Iraq as the most important issue affecting their vote, and majorities of Republicans and Democrats said they wanted a change in approach. Twenty percent said they thought the United States was winning in Iraq, down from a high this year of 36 percent in January.

Even beyond the war, the Times/CBS News poll, like most other polls this fall, contained worrisome indicators for Republicans as they go into the final days of a campaign in which many are bracing for a loss of seats in both the House and the Senate.

In a year when there are many close races, Democrats were more enthusiastic than Republicans about voting and more likely to say they would support their party's candidates, although Republicans were slightly more likely to say they would actually vote.

Fifty percent of independent voters, a closely watched segment of the electorate in such polarized times, said they intended to vote for the Democratic candidate, versus 23 who said they would vote for a Republican.

Among registered voters, 33 percent said they planned to support Republicans, and 52 percent said they would vote for Democrats.

As a rule, generic questions like those, while providing broad insights into the national mood, are often imprecise as a predictor of the outcome of hundreds of Congressional races, where local issues and personalities can shape the result.

Voters said neither Democrats nor Republicans had offered a plan for governing should they win on Tuesday, the poll found.

Yet Americans have some clear notions of how government may change if Democrats win control of Congress.

Beyond a quicker exit from Iraq, respondents said they thought a Democratic-led Congress would be more likely to increase the minimum wage, hold down rapidly rising health and prescription drug costs, improve the economy and — as Republicans have said frequently in these closing days of the campaign — raise taxes.

By a slight margin, more respondents said the threat of terrorism would increase under Republicans than said it would increase under Democrats.

Notwithstanding the clear expectation among members of both parties that a Democratic-led Congress would produce a change in Iraq policy, it was not clear how much influence that might have on Mr. Bush, who as commander in chief would retain the final say.

In addition, while Democrats have coalesced around a general position of finding a way to reduce or end American involvement in Iraq, there is substantial disagreement among Democratic Congressional leaders and candidates about exactly how to accomplish that.

Nearly 75 percent of respondents, including 67 percent of Republicans and 92 percent of Democrats, said they expected that Americans troops would be taken out of Iraq more swiftly under a Democratic-led Congress.

Forty-one percent of respondents said they expected that troop levels would decrease if Democrats won control, while 40 percent said the party would seek to remove all troops. Forty-one percent said they expected troop levels to remain the same if Republicans won, while 29 percent said they thought the United States would send more troops if the Republicans continued to control Congress.

Those findings cut across party lines, but the poll found that Democrats were more likely to say Republicans would increase American troop strength while Republicans were more likely to say Democrats would remove all troops.

Follow-up interviews found clear expectations about the policies each party would pursue in Iraq, even if there was disagreement about which course was correct.

"If the Republicans continue in power, they would probably just want to keep doing what we're doing and doing it longer and harder because the president is Republican and he's the one who sent the troops there in the first place," said Ashley Robertson, 20, a Democrat from Minnesota. "But right now I think it's a bad thing to bring them all home because it's like we went in there to try to help and we're leaving them high and dry and saying clean up our mess."

Pat Atley, 73, a Republican from Florida, said she expected Republicans to press for more troops in Iraq if they stayed in power, although she said she hoped they would not.

"I've always felt we were never going to do any good over there," Ms. Atley said, adding, "I don't think we should increase our troops because increased troops aren't going to do anything except put more of our men and women in jeopardy."

Mr. Bush's overall approval rating was 34 percent, unchanged from a poll three weeks ago, an anemic rating that explains why many Democrats are featuring him in their final advertisements, as well as why some Republican incumbents do not want him at their side.

That approval rating is 9 points below where former President Bill Clinton's was in October 1994 — the election in which Republicans surprised Democrats by taking control of the House — and 28 points below where Mr. Bush's approval rating was on the eve of the 2002 midterms.

In this latest poll, 56 percent of respondents said Mr. Bush's campaigning on behalf of candidates had generally hurt them, as compared with 26 percent who said a campaign visit by Mr. Bush helped.

There was a slight increase, to 38 percent from 34 percent three weeks ago, in respondents who said they approved of how Mr. Bush was managing the economy. Similarly, there was a slight increase, to 44 percent from 40 percent in July, in respondents who said they approved of how Mr. Bush had managed the situation with North Korea.

In a year marked by corruption scandals, 58 percent of voters said corruption was widespread in Washington; 35 percent said the Republican Party had the most corrupt politicians, compared with 15 percent who said the Democratic Party did.

The poll found that the intensity of Democratic support for Democratic candidates was slightly greater than Republican support for Republican candidates, which could give some solace to Democrats who have been concerned that the Republican Party's formidable get-out-the-vote operation would help them eke out victories in close Congressional races. Ninety percent of Democratic voters are planning to vote Democratic, while 83 percent of Republicans said they would support Republican candidates.

In addition, 50 percent of Democrats said they felt more enthusiastic about voting in this election than in previous ones, compared with 39 percent of Republicans.

But 93 percent of Republicans said they were definitely or probably going to vote next Tuesday, compared with 89 percent of Democrats.

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