By Mark Willen, Senior Political Editor April 15, 2008 John McCain's call today for a gas tax holiday this summer is an insult to the intelligence of American voters. He really ought to be ashamed. Sure, it sounds nice, and we can all use a break at the pump, but McCain knows as well as anyone that his proposal would be impossible to implement and a very bad idea to boot. Assume for a second that Congress and President Bush agree tomorrow to adopt McCain's proposal. Then what? It may be easy to change pump prices every day, but the mechanism for separating the federal 18.4 cents per gallon tax and accounting for it is far more complicated. There's no single switch in Washington that can be pulled to make the change all across the U.S. at once. Doing so could take months, even if McCain were already president and marshaled the full force of government to help. But the more important point is that a gas tax holiday is a terrible idea. For starters, the tax goes into the Highway Trust Fund, which is already in danger of going broke next year. McCain's moratorium would move the drop dead date much closer, robbing states and cities of crucial road funding, pushing construction firms across the country into bankruptcy and costing thousands of jobs. It would do significant damage to the economy and delay the recovery. Plus, if McCain is serious about global warming, we ought to be getting people out of their cars, not encouraging them to drive more. Plus, if there's one silver lining in skyrocketing gas prices, it's that they have reduced demand, and that is expected to bring prices down. If McCain's tax holiday is put into effect, it will put upward pressure on demand and prices, effectively shifting the money from the trust fund to the oil companies without helping consumers. McCain's proposal may be effective politically. If Democrats denounce it for what it is, Republicans can accuse them of favoring higher taxes. But deep down, McCain knows what's right. It's a shame he's messed up a chance to start a serious debate about economic policy by pushing a headline grabbing political stunt .