What would be the advantages and disadvantages if President Obama was to issue gold or silver backed certificates instead of injecting trillions into the economy?

Our money will stay as is, but will now include gold or silver backed money as well. I’m not sure how much gold and silver the US is holding, but why not back some money by it rather than adding a crap load of debt? If it is going to turn out to be a good investment, what do we have to worry about?