Mixed Messages Add Anxiety as Deadline Nears in Health Act WASHINGTON - For most Americans, Monday is the deadline to sign up for health insurance that takes effect on Jan. 1. It was supposed to be a turning point in the troubled history of the new health care law, the moment when the spotlight would shift from the federal government's online marketplace to the insurance companies providing coverage to hundreds of thousands and eventually millions of people. Larry Levitt of the Kaiser Family Foundation said people who had enrolled early included some with the greatest needs. The Times would like to hear from Americans who have signed up for health care under the Affordable Care Act. Steve Hebert for The New York Times Sandy Praeger, the insurance commissioner in Kansas, expressed concern for people from high-risk pools. But as the date approaches, a series of decisions by the Obama administration to delay some of the law's most important provisions and to extend some deadlines has caused uncertainty among insurers and confusion among consumers. Already the enrollment of young adults appears to be lagging behind the expectations of federal officials and insurers. And insurers, struggling with problems caused by the chaotic debut of the federal insurance exchange in October, have criticized the administration's last-minute changes, saying they could cause instability in the market. The sudden shifts have sent a mixed message to consumers about the significance of the Monday deadline. They reduce the sense of urgency but not the need for coverage. Accordingly, federal and state officials said they were prepared for an increase in activity on their websites and at telephone call centers as uninsured consumers rushed to beat the deadline. "The Dec. 23 deadline is a huge milestone on the way to coverage that will provide relief and hope to a lot of people," said Andrea J. Routh, the executive director of the Missouri Health Advocacy Alliance, a consumer group. For many, this will be the best Christmas gift they've had in a long time. Julie Bataille, a spokeswoman at the Centers for Medicare and Medicaid Services, said the agency was adding staff, training and outreach efforts across the country. "People tend to have questions and act when they come up against deadlines," she said. President Obama said Friday that "more than one million Americans have selected new health insurance plans through the federal and state marketplaces" since they opened on Oct. 1. The administration had hoped that 3.3 million would be signed up by the end of this month, according to a memo prepared by the Health and Human Services Department in early September. States running their own exchanges, like California, Connecticut, Kentucky and New York, said they had seen a surge in demand in the last few weeks. "Momentum is growing," said Peter V. Lee, the executive director of the California insurance exchange. Friends are telling friends. Families are telling families. Kevin J. Counihan, the chief executive of the Connecticut exchange, said calls to its telephone call center had tripled in the last three weeks, to 6,000 a day. "We are really bracing for Monday," Mr. Counihan said. The Connecticut exchange is increasing its call center staff to 114 from 63. The White House and health policy experts have repeatedly said the new insurance plans need to sign up large numbers of younger, healthier people to balance the financial risks of covering older Americans who require more medical care. Federal officials have not disclosed demographic data on people buying insurance through the federal exchange, but early data from states suggest that people ages 55 to 64 are overrepresented while those younger than 35 are underrepresented. In Colorado, 43 percent of people signing up for private plans in the first couple of months were in the 55-to-64 age bracket. In Connecticut, Rhode Island and Washington, the share was 40 percent. And in California and Kentucky, the proportion was 35 percent. Nationally, about 12 percent of the population is 55 to 64. Larry Levitt, a senior vice president of the Kaiser Family Foundation, said that people enrolling early included some with the greatest needs: people who had been locked out of the individual insurance market because of serious illnesses and those coming from federal and state programs for people with pre-existing conditions. Most of those programs, known as high-risk pools, are scheduled to end next year. Many people who bought insurance on their own have received notices saying their policies were being canceled or discontinued because the policies did not comply with coverage requirements of the new health care law. Those expecting high medical bills had the strongest motivation to overcome the obstacles to buying insurance on the federal exchange.