It's enduring mystery to me why some politicians think that increasing the gas tax is political suicide but implementing an exciting new largely similar but mostly worse tax requiring either additional paperwork/accounting or expensive technology to enforce is a ducky idea.
A gas tax is superior to a VMT tax, it already exists, and it's very simple to nudge it up by a couple of pennies.
Maybe it's similar to the whole health care thing, where they're so convinced that everyone loves their existing insurance so much that they have to come up with some Rube Goldberg plan to preserve it while changing it. With the gas tax, they're so convinced it's impossible to increase it slightly that they think that implementing a New Exciting Tax is preferable.