Increase the gas tax?

So, I don't know if you've been hearing about this, but Hillary Clinton and John McCain have both suggested the country take a holiday from the 18.5 cent per gallon tax on gasoline during the summer months to alleviate prices and help consumers who are already struggling from high fuel costs. Barrack Obama has patently refused to endorse such a plan, saying that it wouldn't really help many people much, if at all, and that the plan is just the same political pandering that Washington always takes part in, instead of making real changes with real results.

From what I've heard and read, Obama's position is the one that most economists and experts in the field are espousing. The gas tax holiday wouldn't alleviate prices, and might actually inflate prices. The reasoning is such: the gas companies are already charging what the market can bear. If you remove the tax from the price of a gallon of gas, that money will instead just go to the Exxon Mobils of the world, and not actually reduce the price. If you're willing to pay $3.49 a gallon now, why wouldn't you in a couple months? The argument made that prices may actually rise is this: with a huge media campaign letting people know the government isn't taking it's cut from your gas bill anymore, people might believe that gas is truly cheaper, and perhaps consume more, and certainly not less. Of course, when demand goes up, and supplies stay the same, then price goes up. Therefore, temporarily repealing the tax could potentially inflate prices, having the opposite effect that was intended.

So, this leads to my question, which follows naturally, I feel: should we raise the gas tax? If all of the above is true, why wouldn't the inverse be true? If lowering the tax would just increase what are already seen as unfairly high profits, wouldn't raising the tax then act to lower their massive profits? If the perception of lower prices would increase demand and thusly price per gallon, wouldn't the perception of high prices lower demand and therefore lower prices?