Kathleen Romig, the Center on Budget and Policy Priorities’ director of Social Security and disability, said the policy choices have become less effective the longer lawmakers have dawdled on a solution. Eliminating the payroll tax cap entirely, without giving additional benefits in exchange for those additional payments, once would have eliminated the shortfall, she said, but that dramatic step would now only cover three-quarters of the gap, according to Social Security estimates.

Another solution would be to increase the payroll tax, but the latest estimate is that it would need to go up 3.44 percentage points, from 12.4 percent to 15.84 percent — a figure that increases year by year. Alternatively, benefits would need to be cut prospectively by more than 25 percent, the Social Security 2023 trustees report says.

If nothing happens, current law mandates an immediate benefits reduction when the "trust fund" is depleted, in about ten years.