Trump–Russia dossier
Fusion GPS, a private investigative firm, provided political opposition research against Trump in two distinct phases, with completely separate funders. Fusion GPS was first contracted by a conservative political website, The Washington Free Beacon, and Steele was not involved in that research. When Trump became the presumptive Republican Party presidential nominee on May 3, 2016, The Free Beacon stopped their backing. Separately, in April 2016, attorney Marc Elias hired Fusion GPS to investigate Trump on behalf of Hillary Clinton's campaign and the Democratic National Committee (DNC).
https://en.wikipedia.org/wiki/Trump–Russia_dossier