According to a report by Politico's Jake Sherman, in 2005 and 2006 former House Speaker Newt Gingrich (R-GA) owed as much as $500,000 to New York-based jeweler Tiffany & Co. -- and his spokesman won't say why.

Confronted with questions about the congressman's less-than-conservative spending on jewelry, Gingrich press secretary Rick Tyler had "no comment."

The debt was reported to the House Ethics Committee by Callista Gingrich, his wife, who worked for the House Agriculture Committee until 2007.

Forms she submitted indicated that the debt belonged to her husband, Politico noted.

It is not clear if the debt has been paid off.

The revelation is likely to be problematic for Gingrich, who's officially a candidate for the Republican presidential nomination in 2012.

He's attempting to position himself as a fiscal conservative, although that a case that now grows more difficult to make, especially to voters who are aware of his personal spending history.

Read Politico's full report.