Procrastinators be warned: Federal health officials plan to stick with the March 31 deadline to obtain health insurance under the 2010 Affordable Care Act. In fact, the U.S. Department of Health & Human Services said earlier today it doesn't have the legal authority to push back the deadline. The department also released its monthly enrollment report, which shows that at least 144,587 Michiganders so far have chosen plans through the Michigan Health Insurance Marketplace, or state exchange — a slice of the 4.2 million Americans who found coverage between Oct. 1 and Feb. 28.