With just three weeks left to sign up under President Barack Obama’s health care law, a major survey tracking the rollout finds that the uninsured rate keeps going down.

The Gallup-Healthways Well-Being Index, released Monday, found that 15.9 percent of U.S. adults are uninsured thus far in 2014, down from 17.1 percent for the last three months — or calendar quarter— of 2013.

That translates roughly to 3 million to 4 million people getting coverage.

Gallup said the share of Americans who lack coverage is on track to drop to the lowest quarterly level it measured since 2008, before Obama took office.

The survey found that almost every major demographic group made progress getting health insurance, although Hispanics lagged.

With the highest uninsured rate of any racial or ethnic group, Latinos were expected to be major beneficiaries of the new health care law. They are a relatively young population and many are on the lower rungs of the middle class, holding down jobs that don’t come with health insurance.

But the outreach effort to Hispanics got off to a stumbling start. The Spanish-language enrollment website, CuidadodeSalud.gov, was delayed due to technical problems. Its name sounds like a clunky translation from English: “Care of Health.” A spot check of the Spanish site on Sunday showed parts of it still use a mix of Spanish and English to convey information, which can make insurance details even more confusing.

All indications point to lackluster Latino numbers, prompting the administration to make a special pitch as the end of open enrollment season approaches on March 31. The president was on Spanish-language television networks last week to raise awareness.

Gallup found the biggest drop in the uninsured rate was among households making less than $36,000 a year — a decline of 2.8 percentage points.

Among blacks, the uninsured rate was down by 2.6 percentage points. It declined by 1 percentage point among whites. But Latinos saw a drop of just eight-tenths of a percentage point.

The Gallup poll is considered authoritative because it combines the scope and depth found in government surveys with the timeliness of media sampling. Pollsters interview 500 people a day, 350 days a year. The latest health care results were based on more than 28,000 interviews, or about 28 times as many as in a standard national poll.

The survey can be an early indicator of broad shifts in society. Gallup saw a modest decline in the uninsured rate in January, and now two full months of data indicate a trend is taking shape.

Gallup said the drop coincides with the start of coverage under the health care law on Jan. 1. The major elements of the Affordable Care Act are now in effect. Virtually all Americans are now required to get covered or risk fines. Insurers can no longer turn away people with health problems. New state-based markets are offering taxpayer-subsidized private insurance to middle-class households.

Medicaid rolls are also growing, with about half the states agreeing to the program expansion in the law. Low-income people who qualify for Medicaid are able to sign up year-round, so the uninsured rate may keep going down even after the end of open enrollment for private coverage.

The administration is citing numbers that are far higher: about 4 million people signing up for private coverage, and 9 million for Medicaid.

But those statistics also include people who already had health insurance and switched to coverage offered under the law. The government numbers also include children, while Gallup focuses on adults.

The survey was based on telephone interviews from Jan. 2-Feb. 28 with a random sample of 28,396 adults aged 18 and older in all 50 states and the District of Columbia. For results based on the total national sample, the margin of error is plus or minus 1 percentage point, larger for subgroups.

(AP)