WASHINGTON – The push to sign up people for health care won't get any easier in Year 2.

The Obama administration needs to improve everything from customer service to Spanish-language outreach if it's to parlay a functioning website and recent enrollment momentum into even more Americans with health coverage.

"Adding new people only gets harder and harder," George Brandes, director of health care programs at tax preparer Jackson Hewitt, said in a telephone interview. "For whatever reason these people sat on the fence."

Eight million people signed up for private plans under the Affordable Care Act through April 19, the U.S. government reported Thursday. The total includes a surge of 910,000 enrollments in the past month highlighted by young, low-income applicants.

The Congressional Budget Office expects an average of 13 million people to enroll in private health insurance plans for 2015 using the marketplaces created under the law. Enrollment surpassed expectations this year, and next year a penalty on people who don't carry insurance will double to as much as 2 percent of income. The federal website that is expected to serve 35 states next year, healthcare.gov, no longer suffers regular malfunctions.

"The most important thing, from a consumer-facing point of view, is: does the front door work, No. 1, and it does now," Karen Ignagni, president and chief executive officer of America's Health Insurance Plans, the industry's ­Washington lobbying group, said in an interview.

About 48 million people in the U.S. lacked coverage in 2012, and indications are that few of them signed up this year. About 5.5 million people who filed applications for insurance through government exchanges and were told they were eligible to purchase a plan never finished the process, according to federal data released last week.

"I don't think we really have the answer for that right now," Mike Hash, director of the Office of Health Reform at the Department of Health and Human Services, said when asked why those applicants didn't sign up.

Enrollment begins Nov. 15

The administration faces challenges to reach those potential customers. The enrollment period for 2015 begins Nov. 15 and is just three months, half as long as this year. The federal government may not have as much money to spend on advertising or on groups that help people sign up. Negative ads and speeches about the law from Republicans leading up to Nov. 4 congressional elections may confuse uninsured Americans, deterring enrollment.

The Spanish-language health-exchange websites still lag behind English versions. Better coordination of enrollment with tax season may raise awareness about the penalties for not carrying coverage. Customer-service representatives at call centers should be trained to better respond to off-script questions, said Tricia Brooks, a researcher at the Georgetown University Center for Children and Families.

"To get to 13 million we want to make sure we don't slide backward at all," she said.