The report from was released Monday, in the final stretch of the government’s effort to sign people up for coverage. After March 31, some who do not have coverage could face a penalty under the law — though, in recent weeks, the administration has created wiggle room to let those who have trouble getting insurance avoid a fine.

The report showed 34 percent of uninsured say they plan to stay uninsured. The most common reason cited was that they consider health insurance to be too expensive. Others are simply opposed to the health care law or think they are healthy enough to go without insurance.

But the poll revealed lingering hurdles for the Obama administration. Seventy-percent of uninsured Americans said they did not know about the law’s subsidies, which are meant to defray at least some of the additional costs from buying health insurance.