Trump has an ambitious agenda that involves the Justice Department, on matters from immigration, to civil rights to border security. Attorney General Jeff Sessions, who was one of his earliest and most vocal supporters, had his choice of Cabinet positions. Sessions has announced he would recuse himself from the Russia investigation, but Comey went out of his way to say that the Justice Department had authorized him to take the unusual step of disclosing it.
The disclosure raises questions about how will Trump navigate his dealings with his attorney general and the department to avoid any suggestion of meddling in an ongoing investigation. At least since Watergate, there have been strict protocols covering contacts between the White House and Justice Department about pending investigations – protocols that Trump’s chief of staff Reince Priebus may already have violated by speaking with Comey and Assistant FBI Director Andrew McCabe about the Russia inquiry.
It also raises the possibility that Trump will get bogged down in questions about the investigation, which could adversely affect his ability to achieve his policy goals. Even initiatives that have nothing to do with Russia or national security could suffer if a Republican Congress is less inclined to fight for his proposals, and there is also the matter of the time and focus responding to such an inquiry requires from the White House.