In reasserting his support for a new government health plan for the uninsured, President Obama stoked the fears of private insurers that they would not be able to compete with a Medicare-like option and might gradually be priced out of existence. The Obama administration has sought to reassure the industry by pointing to the three dozen states that offer their employees a choice between government-backed insurance options and a menu of commercial policies. But health policy experts are deeply divided about whether the state employee plans bear any meaningful resemblance to the public plan options being considered.