Newt Gingrich has spent the past several days assailing Mitt Romney’s business background, suggesting that the former private equity executive “looted” companies and “left people unemployed.”

But here’s an interesting note Gingrich doesn’t mention: Upon leaving Congress in 1999, the former Speaker joined private equity firm Forstmann Little & Co. as a member of its advisory board.

It is unclear how long Gingrich served on the advisory board, or how much he was paid. The campaign has not yet responded to a request for comment.

Forstmann Little was one of the world’s original leveraged buyout firms, although its founder — the late Teddy Forsmann — often railed against what he saw as over-leveraging by rival firms (presumably including Bain). It effectively began winding down operations in 2005, following a legal dispute with the State of Connecticut over failed investments in a pair of large communications companies. Forstmann Little lost the case at trial, but wasn’t required to pay any significant restitution (both deals were done within two years of Gingrich being named to the advisory board).

During Saturday night’s GOP primary debate in New Hampshire, Gingrich said: “I’m not nearly as enamored of a Wall Street model where you can flip companies, you can go in and have leveraged buyouts, you can basically take out all the money, leaving behind the workers.”

Fortune has been unable to determine if Gingrich personally invested in the final Forstmann Little fund (raised in 2001). According to his financial disclosure form, the only alternative investment vehicle he currently has exposure to is a venture capital fund managed by Draper Fisher Jurvetson. Portfolio companies include several cleantech startups that have received Department of Energy loans, including Tesla Motors (TSLA) and BrightSource Energy.

Following the Solyndra bankruptcy, Gingrich called for the resignation of Energy Secretary Chu, adding that he “would have blocked any additional loan guarantees until a full investigation had taken place into the mismanagement and potential corruption in the loan for Solyndra.”

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