WASHINGTON — Americans who lack medical coverage disapprove of President Barack Obama’s health care law at roughly the same rate as the insured, even though most say they struggle to pay for basic care, according to the latest New York Times/CBS News poll.

Fifty-three percent of the uninsured disapprove of the law, the poll found, compared with 51 percent of those who have health coverage. A third of the uninsured say the law will help them personally, but about the same number think it will hurt them, with cost a leading concern.

The widespread skepticism, even among people who are supposed to benefit from the law, underscores the political challenge facing the Obama administration as it tries to persuade millions of Americans to enroll in coverage through new online marketplaces, a crucial element of making the new law financially viable for insurers.

There are several reasons that the uninsured appear to be as wary of the law as the insured, including opposition to the requirement that most people have insurance. Still, nearly six in 10 uninsured said having insurance would make their own health better. And 56 percent said they were more likely than not to get insurance by March 31, the deadline to enroll in coverage or face a tax penalty under the law. Thirty-five percent said they were more likely to pay the penalty.

Overall, support for the 2010 health care law has improved since November, when it dropped to an all-time low of 31 percent in a CBS News poll after the flawed rollout of the federal online insurance exchange. The new poll showed approval of the law at 39 percent and disapproval at 50 percent among the general public.

But with the law’s central provisions set to take effect in less than two weeks, uninsured Americans — precisely those it was meant to help — remain confused about it and fearful that it will increase their health care costs. And nearly six in 10 said they had not researched insurance on the online marketplace, even though, based on the demographics of the sample, many probably qualify for free or subsidized coverage.

“I don’t understand it at all,” said Derrick Stapleton, 47, an independent from Peru, Ind., speaking in a follow-up interview. Stapleton, who is uninsured and out of work, said he planned to sign up for coverage before the March 31 deadline. But he added, “It sounds, from what I understand, that it might not be as affordable as they once thought.”

Even as the insured and uninsured expressed similar misgivings about the law, the uninsured reported starkly different experiences with the health care system. Their responses suggested that they were far more likely than the insured to have trouble paying for medical care, to rely more on emergency rooms and community clinics, and to forgo treatment.

Of the uninsured who said they were not likely to sign up by the deadline, fully half said it was because of the high cost. Twenty-nine percent said they planned to go without coverage because they objected to the government’s requiring it, and 11 percent said they did not need health insurance.

The poll was conducted among 1,000 adults nationwide by telephone from Dec. 5 to Dec. 8 and among 702 uninsured adults from Dec. 4 to Dec. 15.