Sanders acknowledged that his campaign was briefed about Russia's alleged efforts about a month prior. Sanders suggested that Russians were impersonating people claiming to be his supporters online in order to create an atmosphere of toxicity and give "Bernie Bros" a bad reputation, a suggestion that Twitter rejected. According to election-security expert Laura Rosenberger, "Russian attempts to sow discord in the Democratic primary would be consistent with its strategy of undermining Americans' faith in democratic institutions and processes." In March 2020, the University of Wisconsin–Madison and the Brennan Center for Justice published a report indicating that Russia-linked social media accounts have been spreading Instagram posts calculated to sow division among American voters. According to the report, Russian operatives were increasingly impersonating real political candidates and groups rather than creating fictional groups. According to Twitter's head of site integrity, Russian agents also attempted in 2018 to create the impression of more election interference than is actually happening to undermine confidence in the process. Shortly thereafter, the "New York Times" reported that according to American intelligence officials Russian operatives have been stoking via private Facebook groups anger among African Americans, emphasizing allegations of police brutality in the United States, highlighting racism in the United States against African Americans, and promoting and pressuring hate groups, including white and black extremist groups, in order to create strife within American society, though American intelligence officials provided few details about the alleged operations. A CNN investigation found that Russian efforts had partly been outsourced to troll farms in Ghana and Nigeria. Dan Coats appointed Shelby Pierson as the U.S. election security czar in July 2019, creating a new position in a move seen as an acknowledgment that foreign influence operations against U.S. elections will be ongoing indefinitely. Election-security task forces established before the 2018 midterm elections at the FBI, the Department of Homeland Security, the National Security Agency and the United States Cyber Command have been expanded and "made permanent". The Department of Homeland Security indicated that the threat of ransomware attacks upon voter registration databases was a particular concern. Prior to resigning as U.S. Secretary of Homeland Security, Kirstjen Nielsen attempted to organize a meeting of the U.S. Cabinet to discuss how to address potential foreign interference in the 2020 elections. Mick Mulvaney, the White House Chief of Staff, reportedly warned her to keep the subject away from Trump, who views the discussion as questioning the legitimacy of his victory in 2016. Mitch McConnell, the Senate Majority Leader, has blocked various bills intended to improve election security from being considered, including some measures that have had bipartisan support.