Wonkblog's Sarah Kliff breaks down the policy you need to understand about the Affordable Care Act, from politics to premiums. (Kate M. Tobey/(In Play))

Confusion persisted Wednesday around the long-awaited opportunity for Americans to sign up for coverage through new health-insurance marketplaces, with the federal Web site for more than half the states remaining balky and health plans uncertain whether they had any new customers.

The federal site, Healthcare.gov, was sluggish and flashed error messages much of the day. The Obama administration said the delays were simply the result of an initial rush of people flocking to the site — 4.7 million unique visitors in the first 24 hours — while some in the health-care industry suggested that the problem was more serious.

Officials at the White House and the Department of Health and Human Services insisted that some people were able to get far enough into the site to peruse their insurance options, find out whether they qualify for financial help and ultimately enroll in a health plan. But administration officials, for a second day, declined to disclose how many people actually had enrolled and where in the country they live.

Meanwhile, interviews with health insurers, industry consultants, nonprofit groups and people trying to sign up for coverage suggested that the number was very low. Some companies that are offering plans on the federal site said Wednesday that no one had signed up with them.

“Very, very few people that we’re aware of have enrolled in the federal exchange,” said one insurance industry official, who like many in the industry, spoke on the condition of anonymity out of concern for possibly offending the Obama administration. “We are talking single digits.”

A spokesman for one major Blue Cross Blue Shield plan in a southern state said that, as of Wednesday afternoon, it had not received word from federal health officials of any customers who had completed enrollment in the plan — even though a local news outlet had reported about a man who thought he had signed up. So, plan officials didn’t know whether the man’s enrollment was incomplete or whether the federal reporting of enrollment was running behind.

Whether the snags of the opening days — and the apparently small number of people enrolling right away — present a long-term problem is a matter of intense debate, given that consumers may sign up for the new coverage for the next six months.

Some insurers and policy specialists speculated that the small trickle of early enrollments reflects prudent decisions by consumers to shop carefully, exploring the price and coverage under the various health plans newly available to them. “I wonder if, besides the glitches, people aren’t going on to the system and being smart consumers. If they can get on, looking and comparing . . . but let’s not make a decision immediately,” said William Hoagland, senior vice president at the Bipartisan Policy Center and a former top official at the insurer Cigna.

On the other hand, others said that the early kinks, especially if they persist, could undermine consumer confidence in a law that already has sparked fevered political opposition and widespread public confusion. “Everybody will give you a few days,” said Peter Beilenson, the chief executive of Evergreen Health, an insurer that is selling policies on the Maryland exchange. “But by next week, it’s got to be up and running.”

Experiences varied in the states, plus the District, that are operating their own insurance marketplaces.

In the District, access to the online marketplace, D.C. Health Link, remained relatively smooth, although city officials declined to provide figures to show the volume of second-day interest.

Maryland consumers continued to encounter “a significant bottleneck” in creating accounts that are the first step toward shopping on the state’s exchange, according to Joshua Sharfstein, Maryland’s health secretary. He said a central impediment is that Maryland’s system requires online verification of each person’s identity.

Sharfstein said technicians are developing workarounds, such as having consumers provide identity verification to the customer call center. That has led to times when the function to create accounts is not available.

Sharfstein said the exchange has had enrollment in the “double digits.” But, he added, “We know there’s a lot of interest.” On Tuesday, more than 1,000 people showed up at local health and social service departments around the state eager to sign up.

“We’ve been trying incessantly to get online all morning and we can’t get on, we can’t log in,” Linda Cornelius, a worker at the Montgomery County nonprofit Interfaith Works, said Wednesday. She is one of more than 300 specially trained consumer guides in Maryland helping people sign up for Obamacare coverage.

Virginia is relying on the federal exchange, for which no enrollment figures were yet available.

Kentucky, running its own exchange, provided especially detailed enrollment information, saying that it had signed up 2,989 individuals or families, divided roughly evenly between Medicaid and private insurance, according to spokeswoman Gwenda Bond.

Obama administration officials running the federal Web site urged patience. For example, people logging onto the site may run into a “holding page” for a few minutes before they are able to begin their applications. They should not refresh their browsers or leave the page, as they will lose their places in line.

Many people encountering problems have taken them in stride, willing to give officials the benefit of the doubt. For others, frustration has already started creeping in.

Beltsville resident Nancy Jean Beigel, 55, was among about a dozen people selected to stand with President Obama during a brief appearance Tuesday at the White House to tout the law. But after two unsuccessful attempts at signing up for coverage, once Tuesday and once Wednesday, she gave up for the moment.

“It’s a little confusing,” said Beigel, who earns $8,000 a year running a small cleaning service and likely will qualify for free care under expanded Medicaid. “It’s not so great.”

Sarah Kliff contributed to this report.