The fund raises money through a federal tax on gasoline and puts that cash mostly toward building and fixing roads and bridges.
It's expected to run out later this summer, and lawmakers have been talking about ways to pay for infrastructure projects on the books -- and keep the fund solvent for years to come.
Portman says he'd like to see states opt out of some federal rules for how that money can be spent.
"I think Ohio should be able to keep the gas tax that's collected in Ohio and spend it in Ohio," Portman said. "And it would from the numbers that I've been able to develop from the cost of federal projects versus state projects and the amount of bureaucracy and the cost that's taken out when it comes to Washington, I think it would just about solve the short-term problem, and maybe even the long-term problem."
It's one of several ideas. A bipartisan bill in the Senate would raise the gas tax. House Republicans have proposed funding some highway projects with money saved by ending Saturday postal delivery.