By Noam N. LeveyWASHINGTON -- The Obama administration moved Friday to give states more time to submit plans for setting up insurance exchanges in 2013, a central pillar of the health-care law.These exchanges are designed to allow Americans who don't get coverage through work to buy insurance on Internet-based marketplaces much as they shop for airlines tickets today. They were to be operated by states starting next fall so consumers could get insurance starting in 2014.But just 15 states, as well as the District of Columbia, have established an exchange, according to the nonpartisan Kaiser Family Foundation.Several states, mostly led by Republican governors, have indicated they will not run an exchange, however. Ultimately, more than a third of the states are expected to reject the option, forcing the federal government to step in and operate an exchange in any state that elects not to do so.Governors were supposed to provide the Department of Health and Human Services a blueprint for setting up an exchange by Nov. 16. But with many states behind in the planning process, Secretary of Health and Human Services Kathleen Sebelius informed governors in a letter that they could have until Dec. 14 to submit their blueprint."We are committed to providing you with the flexibility, resources and technical assistance necessary to help you achieve successful implementation of your state's exchange," Sebelius wrote.States still must notify the federal government by Nov. 16 whether they intend to run their own exchange or defer to Washington.