Rosenstein needs to look at the political reality.
It is in his interest to work for the people, rather than pledge loyalty to Donald Trump.
He should recognize that the House and Senate Intel Committees are greatly under-staffed. It appears they have no intent to get to the bottom of the Russia/Trump connection. They are simply going thru the motions, unfortunately deceiving a few Democrats along the way.
More than likely, in my opinion, both Committees have some member or members that are reporting directly to the White House as to the progress of each Committee. They are protecting Donald Trump.
Rosenstein's future will be much brighter if he ignores the political pressure from the White House and appoints a special prosecutor to investigate criminal liabilities. If Trump decides to fire him, it will be seen as a badge of courage for standing up and he will be rewarded in the near future. If he allows himself to be pulled into the web of deceit that is the Trump White House, it will be a huge mistake for him.