WATCH: Pete Buttigieg considers taxing people based on ‘distance driven’

Buttigieg was asked a question concerning the gas tax by Senator Rick Scott, and whether he would support raising it.

"All options need to be on the table. As you know, the gas tax has not been increased since 1993 and it has never been pegged to inflation," Buttigieg said. "That's one of the reasons why the current state of the highway trust fund is that there's more going out than coming in."

"Up until now, that's been addressed with general funding transfers. I don't know whether Congress would want to continue doing that, and in the near term, we need a solution that would provide some predictability and sustainability."

Buttigieg acknowledged, however, that hiking the gas tax would not be sustainable over the long run as electric cars become more popular. "There will be questions about whether the gas tax can be effective at all."

After being asked what he would propose to pay for it instead, Buttigieg said that raising the gas tax could be a short-term solution, as could continued funding transfers, but that vehicle-miles travelled could be taxed too.

"A lot has been suggested recently about the idea of vehicle miles travelled. So if we're committed to the idea of user pace, then part of how you might do that is based on vehicle miles travelled." Buttigieg suggested.

"That raises, of course, concerns about privacy and there remains some technological questions too," Buttigieg continued. "I know that that's going to have to be a conversation, not only in the administration but in congress too."

The proposal also raises concerns about incentives and freedom of movement. Governments in more recent times have tried to give tax incentives for motorists to switch to electric vehicles, which would not be as beneficial with a distance travelled tax instead of a gas tax. It would also concern advocates of freedom of movement who would suggest that such a move would also make intranational travel more expensive.