Infrastructure and people's lives have been organised around today's tax regime. America's historically low gas prices mean houses, jobs and retail are spread out over more area, and public transport is comparatively poor.
If gas prices trebled tomorrow, you'll find a lot of hard-working poor people who have to pay three times as much to get to their low-paying jobs.
There will be sob stories on the news about regular people people who can't afford to move closer to work (houses there are expensive now due to high demand) and who can't afford a more efficient car (as they can't pay off the loan on their SUV which is now worth less than the loan value).
Maybe some young people get fuel efficient motorbikes, like in the developing world. There's a rise in road deaths, of course; everyone knows motorbikes are dangerous.
And it won't just be people commuting to work. It'll be more expensive to get to the shops for food - bicycling or walking isn't an option for the hard-working american mother who has to shop for the family, and who has a newborn baby to look after (which is what your political opponents' attack ads will show).
And how do you think that food gets to the shop? On a gas-powered truck of course. And farm machines run on gas as well. Order everything online? The delivery truck runs on gas. You get your trash picked up? Someone's paying to gas up the truck. You're doing construction? Those backhoes and generators all run on gas. Tradespeople like plumbers and builders? Can't carry that roofing ladder on a bus you know. Fire trucks, police cars, ambulances? Gee, I guess they all run on gas. Buses and removal trucks? Same thing. It costs so much to get Jenny to soccer practice now, and how is little Jimmy supposed to get his double bass to after-school orchestra?
Now everything is more expensive, and everyone has less disposable income. People have to get by with less, so they don't go to the restaurant, they make the old car last a few years longer, and the restaurant and car plant have to lay people off, and you've triggered another recession.
Meanwhile, your busy job as a legislator means you still get driven everywhere, so you come across looking like a huge hypocrite.
Now you've put a regressive tax on getting to work, you've caused a rise in traffic accidents, you're anti-family, you've raised the prices of everything, you've triggered a recession, and you're a hypocrite. In exchange you've got the support of the green lobby, but many of them are having second thoughts.
Good luck with your re-election campaign.