A couple observations on the first part of this thread, which discusses potential work-around to the OLC memos that conclude "a sitting President is constitutionally immune from indictment and criminal prosecution."
First, to the argument that the OLC memos "do not necessarily apply to crimes that go to obtaining Presidency itself." While it's true they don't discuss election issues expressly, the first of these memos was written in September 1973, with Watergate reaching a crescendo.
If the 1973 memo wasn't intended to apply to an election crime, like say the president directing the coverup of an election season burglary at DNC HQ carried out by members of his reelection campaign, it seems pretty likely the author would've told us so--probably in bold text.
Second, to the argument that the president might be indicted and then the actual trial proceedings postponed for the remainder of his term, both memos address that possibility in detail and reject it. I don't see how DOJ could adopt this course without reopening the memos first. 
The third point, that the memos don't restrict state law prosecutions is right, of course, and very relevant given Tish James's interest in investigating Trump world. But for federal prosecutors, the OLC conclusion looks like a substantial and essentially unavoidably obstacle.
That's not to say, of course, that I agree with the OLC memo. I don't, particularly its atextual separation of powers argument. (More on this another time.) Hard experience has shown us, unfortunately, that bad and wrong OLC memos can't simply be talked away.
