Years before Fusion GPS became famous for its work on the Trump dossier, the opposition research firm worked for Tom Steyer, the billionaire Democratic donor currently waging a $20 million TV campaign to impeach President Trump.

A Daily Caller investigation reveals that in 2012, Steyer, a hedge fund chieftain and environmental activist, hired Fusion GPS and its founding partner, Glenn Simpson, to conduct an investigation to help pass a ballot initiative aimed at closing a tax loophole for California businesses and funneling money to clean energy projects.

Steyer poured $32 million into “Yes on Prop 39,” a committee he formed to support ballot initiative Proposition 39. The successful campaign made Steyer a rising star in the world of Democratic politics. The party’s most generous donor in the 2016 election cycle — giving more than $90 million to various political action committees — Steyer is said to be considering running for political office.

The connection between Fusion GPS to Steyer and his “Yes on Prop 39” campaign has not been previously reported, and there is almost no public information linking them.

But a Sept. 24, 2012 press release shows that Simpson, a former Wall Street Journal reporter, was part of the “Yes on Prop 39” California Tax Transparency Project team.

The press release touted the Steyer-funded group’s hiring of a team of investigators “to conduct an in-depth inquiry to determine who is responsible for successfully lobbying the state legislature for a corporate tax loophole that rewards out-of-state corporations with tax breaks for creating jobs outside of California.”

In addition to Simpson, the team consisted of Jack A. Blum, an attorney with expertise in financial crimes, former San Diego Tribune reporter Bill Ainsworth, and Pulitzer Prize-winning investigative reporter Russell Carollo.

Simpson, who worked at the Journal until 2009, is billed on the press release as an “investigative reporter” who was the “recipient of several journalism awards.” The announcement makes no mention of his affiliation with Fusion GPS or his occupation as a hired gun opposition researcher.

Simpson did not respond to several requests for comment.