WASHINGTON — The U.S. Department of Transportation on Tuesday asked Congress to end the prohibition on tolling existing interstate highways as a way of paying for their reconstruction, marking a major shift away from how the system has been funded for decades.

The proposal is part of President Obama’s $302 billion infrastructure bill aimed at addressing a looming shortfall in the federal Highway Trust Fund. States are currently able to toll interstates only to add lanes, but many simply don’t have the funds they need to widen or rebuild the oldest sections of interstate, and nor does the federal government.

Transportation Secretary Anthony Foxx said Tuesday that the federal Highway Trust Fund is set to run out of cash in August, a scenario that would hurt most states. According to the American Road and Transportation Builders Association, a trade group, 31 states rely on federal funds for more than half their highway and bridge improvements.

Longtime advocates of expanded tolling lauded the proposal.