In other words, Perez, despite his progressive credentials, is viewed — with good reason — as a reliable functionary and trustworthy loyalist by those who have controlled the party and run it into the ground, whereas Ellison is viewed as an outsider who may not be as controllable and, worse, may lead the Sanders contingent to perceive that they have been integrated into and empowered within the party.
But there’s an uglier and tawdrier aspect to this. Just over two weeks after Ellison announced,
the largest single funder of both the Democratic Party and the Clinton campaign — the Israeli-American billionaire Haim Saban — launched an incredibly toxic attack on Ellison, designed to signal his veto. “He is clearly an anti-Semite and anti-Israel individual,” pronounced Saban about the African-American Muslim congressman, adding: “Keith Ellison would be a disaster for the relationship between the Jewish community and the Democratic Party.”
https://theintercept.com/2017/02/24/key-question-about-dnc-race-why-did-white-house-recruit-perez-to-run-against-ellison/