washington u.s. government cost could increase 2.3 billion 2018 congress president donald trump decide fund obamacare-related payments health insurers accord study release tuesday kaiser family foundation payments amount billion fiscal year 2017 help cover out-of-pocket medical cost low-income americans purchase insurance individual insurance exchange create affordable care act often call obamacare trump threaten withhold payments force democrats negotiate table healthcare bill replace obamacare also say fund subsidies democrats agree fund propose border wall mexico part efforts pass government fund bill week avert shutdown democrats reject conditional offer deal make part federal government shut 12:01 saturday payments subject pending republican lawsuit appeal obama administration put hold trump take office government could save 10 billion revoke payments kaiser say insurers remain market would hike premiums nearly 20 percent cover losses kaiser find government would spend 12.3 billion tax credit help pay americans premium cost net increase 23 percent federal spend marketplace subsidies projection assume insurers remain marketplace next year health policy experts say without payments many insurers could afford stay market likely exit would leave u.s. counties without insurer aetna aet.n unitedhealth group inc unh.n humana hum.n already exit state exchange 2017 say next year well government cost could rise 2.3 billion without obamacare payments study