Oh, don't worry, RedState— I believe every word out of the mouth of a Deputy Commissioner of the IRS.
...Deputy IRS Commissioner John Dalrymple said the party identification information was automatically collected through a “database platform” supplied by an outside contractor that targeted voter registration rolls among other things as it searched for people who aren’t paying their taxes.
“This information is appropriately used to locate information on taxpayers whose accounts are delinquent,” he said.
I'm sure it's used for exactly that purpose. For some definition of "appropriate" in that context...