Newt Gingrich's presidential campaign is off to a rocky start, partly because the Gingrich-Tiffany's story just won't go away.

The Washington Examiner reports today that Christy Evans, a top staffer for Gingrich when he was the Republican Whip (1989-1995), is a registered lobbyist for Tiffany's, the luxury jewelry company that extended Mr. Gingrich a very large line of credit.

Evans, who works for the storied lobbying firm Cassidy & Associates, has represented Tiffany's on mining issues since 2000, according to official records.

As we noted yesterday, Tiffany's gave Mr. Gingrich a $500,000 line of credit while his wife, Callista Gingrich, was the clerk of the House Agriculture Committee, which has jurisdiction over the mining agencies that Evans was lobbying on behalf of Tiffany's. Mrs. Gingrich left her position on the committee in 2007.

Mr. Gingrich's unusual relationship with the high-end jeweler is now threatening to derail his 2012 presidential campaign. A new Public Policy Polling survey finds Gingrich "has completely tanked with Republican voters." Only 38% of Republican voters have a favorable opinion of the former House Speaker, and 45% have an unfavorable one.