You say the director of Homeland Security is a Republican? Funny then that he would've worked on Obama's campaign:

"Secretary Johnson was appointed by President Obama on December 23, 2013....  Previously, Secretary Johnson was appointed by President Obama to be General Counsel of the Department of Defense from 2009 through 2012.... Johnson was a top fundraiser for Obama’s 2008 presidential campaign and was part of a prominent Democratic fundraising circle in New York.  In 2008 he served as a part of President-elect Barack Obama’s transition team before being appointed as the top lawyer for the Department of Defense."

Comey IS a Republican, but he's also the guy that, shortly before the election, announced that the FBI was going to re-open the investigation into Hillary Clinton's emails. What better way to take the heat off himself for interfering in the election than to accuse the Russians of doing so? And regardless of his politics he owes his job to Obama.