The U.S. transportation secretary says indecision by Congress about how to pay for programs is again threatening to set back or shut down road and transit projects across the country.

That could result in widespread layoffs of construction workers and delay needed repairs and improvements.

Secretary Anthony Foxx kicked off an eight-state bus trip in Ohio this week to whip up public support to keep federal transportation aid flowing to states. Congress will have to act fast. The Highway Trust Fund, the source of much of the aid, is forecast to essentially run dry sometime before the end of the federal fiscal year on Sept. 30, possibly as early as July.

If that happens, the federal government will have to slow down or even halt payments to states.