Fuel tax would be part of infrastructure plan
My guess is that the White House is floating this for a reason. A fuel tax would lower gasoline demand at the margins and that would be a small drag for crude in the bigger picture.
The US has some of the world's lowest gasoline prices for a developed nation. However it also has larger cars on the road that other developed nations and a well-established anti-tax lobby.
I'll be surprised if Republicans pass a higher gasoline tax but such a move would make Trump appear to be more of centrist ahead of 2020 elections so it's possible.