Hillary Clinton's presidential campaign and the Democratic National Committee helped fund the research behind the infamous dossier that alleges ties between President Trump and Russia, according to a report.

Marc Elias, a lawyer for the Clinton campaign and the DNC, retained the political consulting firm that commissioned Christopher Steele, the dossier's author, the Washington Post reported.

That agreement reportedly began in April 2016. Elias and his law firm, Perkins Coie, funded the research by the firm Fusion GPS that led to the dossier through October 2016.

A still-unknown Republican donor initially funded Fusion GPS's research.

The dossier alleges extensive ties between the president and Russia, but its contents are unverified. It has become the subject of three separate investigations into Russian interference in the 2016 presidential election. Trump has called the document false.