The program has its problems, but is largely considered effective by most — except for a vocal group of deficit hawks in Congress and in Washington "think tanks" who state that an unfunded entitlement like Medicare is unsustainable and must be addressed now. They frequently cite an estimate from the Medicare Office of the Actuary study that Medicare will cost $37 trillion over the next 75 years as the major reason that privatization is necessary. They also cite that the Medicare Trust Fund, which pays for hospital care, will become insolvent. The only option, they argue, is to shift responsibility for the program to the private sector that will use market competition to deliver guaranteed benefits. The effort is linked to the repeal of the Affordable Care Act, which for years has been the primary domestic policy agenda of Republicans in Congress.