There certainly is a pricing relationship between residual oil and crude oil. There is also a correlation between resid and nat gas that was fairly constant until this year when resid hit 130 percent of gas. Its about 113 percent right now.
Look for the Democrats to attempt this maneuver...
Since gas prices are largely the result of the surging price of a barrel of crude, and that is a product of speculation in the futures market, I would expect them to propose some draconian surtax (90% or so) on profits earned from the trading of energy futures.
This would have the effect of frightening a vast number of US based speculators out of the market, and the resulting sell-off from the world’s wealthiest country would force the price of a barrel of crude to drop like a rock. The bubble will have been pricked and will deflate. This is precisely how they have blown-up markets in the past and I am surprised it is taking them so long to think of it.