In mid-June, respondents were evenly divided when asked whether they thought President Obama's health plan was a good or bad idea. In the new poll, conducted July 24-27, 42% called it a bad idea while 36% said it was a good idea.
Among those with private insurance, the proportion calling the plan a bad idea rose to 47% from 37%.
Declining popularity of the health-care overhaul reflects rising anxiety over the federal budget deficit and congressional debate over the most contentious aspects of the legislation, including how to pay for it. The poll also shows concern over the role of government in determining personal medical decisions.
Trying to regain momentum, Obama is shifting his pitch to new consumer-protection rules for insurance companies, part of a bid to win over Americans who already have coverage.
David Axelrod, one of the president's top advisers, acknowledged that the White House's months-long focus on controlling medical costs hasn't worked. "Consumer protections are a lot more tangible," he said.
On Wednesday, Democratic leaders in the House reached accord with conservative party members to move their bill through the last of three committees, although the full House won't vote on the measure until at least September. "Failure is not an option," said California Democratic Rep. Henry Waxman.
The White House is eager to show progress and build public support before Congress breaks for summer, when opponents plan to continue their campaign. "If this bill hangs out there over the August recess my guess is it will get shredded," House Minority Leader John Boehner (R., Ohio), said.
In the Journal poll, only two in 10 people said the quality of their own care would improve under the Obama plan; just 15% of those with private insurance thought it would. Twice as many overall, and three times as many with private coverage, predicted their own care would get worse.
"You can't pass a substantial health reform unless privately insured people see there's a benefit for them," said Bill McInturff, a Republican pollster who conducts the poll with Democrat Peter D. Hart.
Support for former President Bill Clinton's health plan hovered in similar territory in 1994 on its way to defeat. But the Clinton plan never made it as far in Congress as the Obama effort has this year. Indeed, the poll showed strong support among respondents for ideas common to all of the pieces of health-care legislation being considered by Congress.
When given several details of the proposal, 56% said they favored the plan compared with 38% who oppose it.
The description given to poll respondents didn't include a public-insurance plan, which divides the public, nor specifics about what income levels might be taxed to fund the plan.
The poll had a margin of error of 3.1 percentage points for the overall sample.
President Obama has focused sharply on cost control for businesses and Americans who have seen premiums rise faster than wages.
White House officials believed this would give those with insurance a stake in the debate.
But those efforts have been hurt by the debate in Washington, which has been dominated by the $1 trillion, 10-year price tag for covering the uninsured. That makes it hard to persuade people that the bill will lead to reduced costs, said Mr. Axelrod.
"People are properly skeptical about any proposals out of Washington that speak to cost because they've been singed by past experience," said the senior Obama adviser.
At a town hall meeting in Raleigh, N.C., Wednesday, the president outlined a series of policies, many of which the insurance industry has agreed to accept.
The president said, for example, he wants rules that would require insurers to cover people with pre-existing conditions, cap out-of-pocket expenses, bar insurers from dropping people who become seriously ill, ban annual or lifetime coverage caps, and allow adults to stay on their parents' plans through age 26.
"If you've got health insurance, then the reform we're proposing will also help you because it will provide you more stability and more security," President Obama said.
On the question of how to pay for the measure, the poll found only one idea with majority support: a surtax on the rich, the approach taken in the bill moving through the House, but which isn't expected in the Senate version.
Public support for fining businesses that don't offer insurance dropped from last month, with half of those polled now in favor. Only four in 10 liked the idea of taxing insurance companies that offer particularly generous health plans, an idea that has gained currency in the Senate Finance Committee.
The poll found that Mr. Obama's overall ratings have fallen amid worries over the economy, with the decline due almost entirely to dwindling support by Republicans. His score is solid by historical standards but no longer at the high-flying levels of his early weeks.
Overall, Obama's ratings fell on a series of measures. His job approval now stands at 53%, down from a high of 61% in April. That is three points higher than President George W. Bush had in June 2001, following a contentious election victory.
The proportion of people who said it was very or fairly likely that Mr. Obama would bring "real change" dropped to 51% from 61% in February. The share of those who said he could be trusted to keep his word fell to 48% this month from 58% in April.
Mr. Hart, the Democratic pollster, said rising concerns over employment and the economy explained Obama's falling ratings.
"He seems embroiled in so many of the issues of the day without much sense of relief on the economic front," he said.
The poll also found a rising sense of partisanship. More than three in 10 surveyed said the current Congress has been more partisan and divided than in the past, compared with just 11% who said it has been less partisan.
In February, people were more likely to blame Republicans by a two-to-one margin. This month, they were divided over who to blame, with most saying both parties were at fault.
On other issues, the poll found:
Strong support for Sonia Sotomayor, the president's nominee for the U.S. Supreme Court. Forty-four percent of people said they strongly or somewhat supported her confirmation with 30% opposed.
Falling support for the economic stimulus plan, with 34% in favor, down from 44% in February; 43% now say it is a bad idea.