Only 15 U.S. states plan to operate health insurance exchanges under President Barack Obama's reform law, leaving Washington with the daunting prospect of creating and operating the new online marketplaces in at least two-thirds of the country. On the eve of a federal deadline for states to say whether they will run their own exchanges, 11 other states have informed the administration that it should plan to be heavily involved in setting up private health insurance markets within their borders, said Gary Cohen, director of the Center for Consumer Information and Insurance Oversight, on Thursday.