There is no need for a crime or a coverup under the Federal Stature. The language is very broad. If what you are doing is trying to impede justice, then you could be charged with obstructing justice. Trying to stop an investigation of a criminal investigation by the FBI would be an example. The investigation of Flynn is a criminal investigation according to what the FBI and Comey have said to the Senate. So trying to stop or affect the investigation of Flynn could be obstructing justice.