On a separate issue, Gingrich told reporters that he paid 31 percent of his 2010 income in taxes, more than double the 15 percent Romney said he pays. A Gingrich spokesman said the 31 percent was the effective federal rate on his income. Gingrich declined to criticize Romney on the tax issue, saying instead that it made the case for his own proposal to put in place an optional 15 percent flat income tax. "My goal is not to raise Mitt Romney's taxes, but to let everyone pay Romney's rate," he said.