Newt Gingrich's "standard" $500,000 line of credit with upscale jeweler Tiffany & Co. is fast becoming a classic Washington political "mini-scandal."

Jeff Stein at SpyTalk reports that while Tiffany's was extending Callista Gingrich an interest free loan for hundreds of thousands of dollars, the diamond firm was spending a lot of money to influence mining policy in agencies under the jurisdiction of the House Agriculture Committee, where Mrs. Gingrich worked until 2007.

Mrs. Gingrich listed a "revolving charge account" at Tiffany's in the liability section of her financial disclosure form in 2005 and 2006, indicating that it was her husband's debt. According to official records, Tiffany's annual lobbying costs rose from about $100,000 to $360,000 between 2005 and 2009 .

The Washington Post reports that Tiffany's does offer 12-month interest free loans to major clients, as well as a "revolving credit card agreement with state-specific interest rates." The Gingrichs' "revolving charge" account was open for two years, but we know the Gingrichs' loan was interest-free because Mr. Gingrich said so on CBS' "Face The Nation" this past Sunday.

So was the loan actually a lobbying expense?

Felix Salmon writes:

"...It seems unwise, to say the least, to accept an interest-free loan of more than $250,000 from a company which is lobbying your committee — no matter how rare or common such loans might be….But now we do know that, the loan begins to look more like an undisclosed lobbying expenditure on the part of Tiffany. Which in many ways is even worse for Gingrich. There must be official rules about accepting interest-free loans from companies lobbying your committee. Is there a case to be made that Callista Gingrich broke those rules?"

Either way, the Tiffany's story has damaged Mr. Gingrich's nascent 2012 presidential campaign. If it gets worse and becomes a full-fledged "scandal," it could bring Mr. Gingrich's campaign to a close.

UPDATE:

Rick Tyler, press secretary for Newt Gingrich's 2012 campaign, forwarded us a statement from Tiffany & Co. spokesman Carson Glover, which denies that the jewelry company ever focused its lobbying efforts on the House Agriculture Committee. From what we can tell, his claims are valid. Most mining issues are handled by the House Natural Resources Committee, not the Agriculture Committee.

Here's the statement:

"Tiffany's lobbying efforts have been focused on the reform of the General Mining Law of 1872 (to fairly compensate taxpayers for metals extracted from public lands and to better protect the environment from the impact of hard rock mining) and the clean-up of abandoned mines. We had no reason to lobby the Agriculture Committee and we did not. Nor did anyone at Tiffany & Co. (or Cassidy & Associates on behalf of Tiffany) ever speak to Speaker Gingrich or Mrs. Gingrich about either of these matters. Our focus has been on the Natural Resources Committee which has jurisdiction over these matters. The one and only meeting with the Forest Service on the matter of Mining Law reform was in response to an invitation by Dale Bosworth, Chief of the Forest Service, as a result of our Open Letter to him in the Washington Post that appeared on March 24, 2004.

To re-iterate, there is nothing unusual or extraordinary about the credit extended to Speaker Gingrich. Last year, Tiffany & Co. extended credit to over 1,000 customers on identical terms."