Despite Congress blocking a cut in Medicare payments to doctors, it has done nothing to solve the fundamental problem that caused the cut. The issue will now come back to haunt the next president and the next Congress, lawmakers and health policy experts say. Democrats and Republicans agree that the formula for paying doctors is broken, but say fixing it would be expensive. Lawmakers are pleading with physicians' groups to come forward with a comprehensive proposal, but that could be difficult because any new formula would almost surely produce winners and losers among doctors.