Roger Stone is a longtime Republican Party operative who advised President Donald Trump, both formally and informally, throughout the 2016 presidential election. Stone, who co-founded the lobbying firm of Black, Manafort, Stone, and Kelly with Paul Manafort in the 1980s, reportedly played a major role in ensuring that Manafort joined the campaign and ultimately became its chairman. Though Stone left the campaign in August 2015—accounts differ as to whether he resigned voluntarily or was fired for drawing attention away from Trump–Stone and Trump remained in close contact throughout the election. Stone has also claimed to have communicated during the campaign with both Guccifer 2.0, the Russian operative reportedly behind the DNC and Podesta hacks, and Julian Assange, and repeatedly evinced advance knowledge of information from hacked emails that would ultimately appear on WikiLeaks. Stone has denied that there was any collusion between the Trump campaign and the Russian government.