In this April 17, 2014, file photo, President Barack Obama speaks at White House in Washington. The Obama administration celebrated when sign-ups for the health care law crossed the 8-million mark after a stumbling start. But most Americans are unimpressed. A new Associated Press-GfK poll finds that public opinion remains deeply negative. One bright spot: Most of those who signed up say premiums are about what they expected, or lower. (AP Photo/J. Scott Applewhite, File)

President Barack Obama celebrated when sign-ups for his health care law topped 8 million, far exceeding expectations after a slipshod launch. Most Americans, however, remain unimpressed.

A new Associated Press-GfK poll finds that continues to run deeply negative on the Affordable Care Act, Obama's signature effort to cover the uninsured. Forty-three percent oppose the law, compared with just 28 percent in support.

The pattern illustrates why the health care law remains a favored target for Republicans seeking a Senate majority in the November elections.

The poll does have a bright spot for the administration: Those who signed up for coverage aren't reeling from high costs. Most said they found premiums in line with what they expected to pay, or even lower.

But even that was diminished by another finding: More than one-third of those who said they or someone in their household tried to enroll, were ultimately unable to do so. For the White House, it's an uncomfortable reminder of the technical problems that paralyzed the HealthCare.gov website for weeks after it went live last fall.

The example of business owner Henry Kulik shows some of the cross-currents of public opinion.

Kulik is disabled as a result of Lou Gehrig's disease, a condition that destroys the brain's ability to control muscle movement. His family runs several stores that sell ice cream and other summer refreshments in the Philadelphia area.

Kulik says he doesn't believe the federal government should require people to carry health insurance, as the law does. And he can understand worries about the cost to taxpayers. On the other hand, he's been able to slash what his family pays for health insurance by purchasing coverage through the law's new insurance markets and by taking advantage of tax credits to lower the premiums.

Before the law, his family was paying $2,400 a month. Now it's several hundred dollars. And Kulik says the insurance for himself, his wife, and three children is comparable to what they had before.

"I think there is a lot of misinformation," he says.

Obama's health care law offers subsidized private coverage to middle-class people who have no health plan on the job, and it expands Medicaid to pick up low-income uninsured adults. But last fall's launch of new markets was paralyzed technical problems. The debacle contributed to the departure of secretary Kathleen Sebelius.

After Congress approved the law in 2010, a political backlash over its Medicare cuts, tax increases and new regulations helped Republicans win the House. This fall the GOP is following a similar strategy with the Senate at stake.

"Republicans hold an advantage on this issue among people who feel strongly about it," said Robert Blendon of the Harvard School of Public Health, who follows opinion trends on .

Still, just 17 percent of poll respondents said the law will be completely repealed. While that represents an increase of 5 percentage points from March, the poll found that 67 percent believe the will be implemented with changes, whether major or superficial.

The poll found that sign-up success translated into higher approval for the . Among those who succeeded in purchasing coverage, 51 percent back the , compared with 30 percent among those who tried to sign up and weren't successful.

The AP-GfK Poll was conducted May 16-19, 2014 using KnowledgePanel, GfK's probability-based online panel designed to be representative of the U.S. population. It involved online interviews with 1,354 adults, and has a margin of sampling error of plus or minus 3 percentage points for all respondents.