Senate Votes to Keep Ethanol Tariff

Andy Roth of The Club For Growth on a US Senate vote to keep a tariff on ethanol imports. If lawmakers believe ethanol is good for the environment (the evidence is mixed, but government mandates and subsidies for ethanol indicate that lawmakers support ethanol use) and reduces "dependence on foreign oil", why have a tariff?

I noted that both PA Senators (Specter and Casey) voted to oppose free trade, and the presidential candidates (McCain, Obama, Biden and Brownback) all did not vote - not with the Iowa primary coming up.