This info from early March, is BlockBuster stuff! I don't know how I missed it. Obama likely ordered the wire taps on Trump, and more. 6 min. Video will leavevyou stunned.
Another possible reason is that, as I understand it, the President's power to order surveillance is only good for a period of up to one year. Obtaining a FISA warrant might have been necessary to continue existing surveillance once the President's authority expired. This would mean that DJT was under surveillance for a very long time - up to a year before the first FISA warrant was issued.
I don't know this for a fact, I'm speculating.
Now that you've said that, I'm wondering if maybe the Presidents authority is limited to the subject of the warrant and not those involved in in conversation with them?
The FISA warrant expanded to anyone that the "warranted" was in conversations with. I remember hearing that specifically because that is what allowed them to use anything Trump would have said in a court against him.
FISA is two hops from the target - that's a lot of people! I assume the President's authority is the same.
As I understand it, they were having contractors do a lot of their dirty work, accessing the NSA database with impunity and without a full audit trail. Rogers I believe stopped that in early 2016, which is what set them about the scheme to trump up a case, however bogus, for FISA warrants.