But the Times/CBS poll nonetheless underscores a national trendline in which the economy remains the dominant force in the campaign, regardless of outside events like the Supreme Court ruling on Mr. Obama’s health care law or the daily sticks-and-stones of the trail.

In a reversal from the Times/CBS Poll in April, more Americans say they disapprove of the way Mr. Obama is handling his job, 46 percent, than say they approve of it, 44 percent, although the difference is within the poll’s margin of sampling error.

Yet there are some hopeful glimmers for Mr. Obama, who is viewed in this poll as the advocate for the middle class. For instance, just over half of the voters said that his policies were improving the economic picture now (17 percent) or would in the future (34 percent).

And he maintains an advantage over Mr. Romney when it comes to the question of whether he cares a lot or some about the problems of everyday Americans — 63 percent said he did, compared with 55 percent who said the same of Mr. Romney.

A plurality of Americans, 49 percent, agree with Mr. Obama’s assertion that the Bush-era tax cuts should continue on adjusted gross annual income of $250,000 and less. More than a quarter say the cuts should stay in place for all income groups; 17 percent say they should expire altogether.

Mr. Romney has ample challenges, too, with the poll showing that he has yet to build up a positive image of his own as Mr. Obama seeks to build a negative one for him.

While more than half of Mr. Obama’s voters said they strongly supported him, fewer than a third of Mr. Romney’s said the same about him. More than a third of his voters said they were voting for him because of their dislike for Mr. Obama, while fewer than 10 percent of Mr. Obama’s supporters said they would vote for him out of dislike for Mr. Romney.