washington trump administration thursday issue final rule shorten obamacare enrollment period give insurers say need individual insurance market likely make hard consumers purchase insurance healthcare experts say could also raise out-of-pocket medical expense experts say give insurers flexibility determine value coverage rule take effect late year come president donald trump republicans congress renew efforts repeal replace affordable care act commonly know obamacare effort pass bill u.s. house representatives fail last month issue division u.s. department health human service first propose february rule aim aid insurers lose hundreds millions dollars individual insurance market set obamacare several major insurers include humana inc aetna inc announce plan exit state exchange 2018. insurers welcome rule say still much uncertainty market wednesday trump tell wall street journal may withhold obamacare payments insurers amount billion year force democrats back negotiate table marilyn tavenner president chief executive america health insurance plan say statement fund payments must continue uninterrupted otherwise say premiums rise 20 percent across market insurers would drop exchange change thursday final rule include shorten open enrollment period obamacare plan also make hard people enroll outside period allow certain circumstances pregnancy move rule could also allow insurers collect unpaid premium payments make tough people move insurance plan accord healthcare industry experts insurers say game system create unprofitable mix healthy sick customers rule also give state broad authority remove federal government role oversee doctor hospital network include insurance plan republicans say healthcare reform overhaul must give state flexibility affordable care act enable 20 million americans gain insurance mostly individual insurance market set law expansion medicaid government health insurance program poor disable trump administration issue final rule strict obamacare enrollment