When, in a CNN interview, Mitt Romney's senior adviser Eric Fehrnstrom was asked about the possibility of Romney's recent conservative positions alienating independent voters in a general election, and Fehrnstrom said, "It’s almost like an Etch a Sketch. You can kind of shake it up and we start all over again," he was using a very powerful (and dangerous) tool: a simile.
See the Vocabulary.com Dictionary page for simile to review what a simile is, where it comes from, and what distinguishes one from a metaphor.