Politicians bring it up continually. Groups have spent millions of dollars promoting — and denouncing — it on television. President Obama is out lauding it virtually every week.

Yet Americans are stubbornly confounded about the health-care law known to many as Obamacare.

“Never heard,” said Lenard Pringle, 54, a Greenbelt resident who said he was not aware of any changes coming to the health-care system. He did not know that in a few months, he will be eligible for Medicaid, the state-federal health insurance program for the poor that is expanding under the law.

He is not alone. More than six in 10 Americans say they do not have the information necessary to understand the changes the law will bring, according to a new Washington Post-ABC News poll.

The results underscore the tough job that lies ahead for the administration, which aims to coax 7 million uninsured people to sign up for coverage by the end of March. This summer, many of its allies embarked on public relations campaigns meant to educate people that they can sign up for health-care plans and perhaps qualify for government assistance starting in the fall.

Among those promoting the law are insurance companies. Evergreen, a new Maryland-based health co-op, has been approaching people in areas with large concentrations of uninsured people to tell them about the law and urge them to sign up with Evergreen.

Pringle, who was waiting at a bus stop in Greenbelt on Wednesday, said he is unemployed and does not have health insurance. Whenever he needs to refill his prescriptions for diabetes and blood pressure medications, he picks up an odd job, such as cutting grass, to pay for them. Sometimes, he said, he goes without his pills.

An Evergreen worker handed him a brochure, explaining that he would probably receive free coverage next year through Medicaid. Pringle had one question: “What number do I call?”

The confusion stretches across age, race, gender, party affiliation and income groups, according to the poll. It also cuts across geography, which is significant because some states are promoting the law more actively than others.

Even some supporters of the legislation are unclear about what it will do.

“I think if you have a serious illness, you should be entitled to a doctor,” said Joan Fernandez, 62, of Deep Water, Mo., a poll respondent who said she does not know what to expect from the law. “I don’t know how Obamacare would affect anything like that, but hopefully it would.”

White House officials say it is not surprising that people are confused, because health insurance is confusing and specific information about policies and rates will not be available until Oct. 1, when open enrollment begins. People will then have six months to comply with the requirement that virtually every American have coverage or pay a fine.

Chris Jennings, White House coordinator for health-care reform, said the administration will begin its big public information push after Oct. 1 so people can find out online how the law will affect them.

“People engage when they need to take action,” Jennings said in a statement. “Their lives are very busy, they have many other priorities in the here and now, and when they engage they want to have the information necessary to make an informed choice.”

Overall, the public remains deeply divided about the law, according to the poll. Slightly more than half of Americans oppose it, while just over four in 10 support it, a chasm that has hardly budged since the legislation was passed more than three years ago.

A majority of Americans say the law has not changed their health-care costs or quality, despite efforts by Republicans to paint it as costly, and remarks by Obama emphasizing ways the measure has improved care.

According to a recent poll by the Pew Research Center, awareness of the health insurance marketplaces is relatively low, with 51 percent of respondents knowing they will be available. That percentage shrinks to 44 percent in states where the government is not actively promoting the law.

The lack of awareness is prevalent among those who would be affected most greatly, according to Pew, which found that only half of the uninsured were aware of the exchanges or the subsidies for low-income people.

Confusion persists despite a number of high-profile efforts to get the word out. In Maryland, health officials announced a partnership with the Baltimore Ravens. Enroll America, a large nonprofit with White House connections, has been going door to door in a number of states and earlier this summer posted an ad in Times Square.

Evergreen, the Maryland health co-op, estimates it has reached 10,000 people through its canvassing efforts.

Obama has tried to highlight the law’s benefits. On Thursday, in a speech to his Export Council, he praised the legislation and said it is “starting to bear real fruit.”

Advocates say some of the confusion could arise from the fact that the marketplaces are not necessarily being promoted as Obamacare, or its formal name, the Affordable Care Act. So people may know more than they think when asked about their familiarity with the health-care law.

In Oregon, for instance, health officials this summer mounted a whimsical $3.2 million television ad campaign that never mentioned Obamacare. Rather, it used the state’s quirky music scene to promote state pride and good health, and to drive people to the marketplace’s Web site and hotline.

“We’re building a product that’s for Oregonians and by Oregonians,” said Amy Fauver, spokeswoman for Cover Oregon. “We don’t really need to get involved in the national political debate about the Affordable Care Act.”