It's tough to understate the impact high gas prices can have. With higher prices, consumers have less disposable income and feel poorer, but that lowered disposable income also ripples through the rest of the economy, as less will be spent in other sectors (dining, movies, etc.)
If gas prices spike into the $4.50-$5.00 range, it's really bad news for the economy - and bad news for Obama, too, heading into the fall elections. Especially since he's seemingly done nothing to help lower gas prices. Prediction markets were giving him over a 60% chance at reelection (62% at the highest point a couple weeks ago) at one point, but that's now down to 59%.