The question is whether the subjunctive carries forward into subordinate clauses that are governed by a completely different subordinate conjunction.. In English, it generally does not.
Let's take your initial fragment:
- And, that's if he could get elected after 35% of Americans turned out in opposition to both parties and a new popular movement was seeded.
And rewrite it into something easier to analyse. Here is the simple version:
- If he were elected, then he would collect.
That part, I trust, is not suspect; this sort of if construction triggers the past subjunctive was > were in the if part.
The problem is when you branch off a new clause subordinate to something that's already in the subjunctive. Do you keep the mood, or reassess, perhaps according to which conjunction you use?
This leaves these two possibilities:
- If he were elected after a new movement was seeded, then he would collect a bountiful harvest.
- If he were elected after a new movement were seeded, then he would collect a bountiful harvest.
It may be that both are acceptable, with the second being more hypothetical.
Here is a bit of evidence that the fancier were-following-after construct does exist in the wild.
- Whereas a spin-1 object returns to its initial configuration after it is rotated a single time, a spin -1⁄2 particle would do so only after it were rotated twice. [citation]
I dunno. To me it sounds extremely legalistic to use the subjunctive after after. Mind you, it did used to happen. Here is Sir Thomas More:
- But still for any power that reason hath to perceive the cause, she shall judge it impossible after she prove it true but if she believe her eye better than her wit. [citation]
Although that is the present subjunctive, like "till death do us part", which we really don't use for those sorts of clauses, so the full example doesn't apply to the question of past subjunctive being asked here. But you can see what I mean by how old-fashioned it sounds. Here is a source from the 17th century that uses
- That if it were lawful to keep a right heir from his kingdom, in respect of conscience, it was as lawful to remove him after he were established. [citation]
Jumping forward a couple of centuries, here's Jane Austen:
- But she would not make up her fire; that would seem cowardly, as if she wished for the protection of light after she were in bed. [citation]
So ok, you can do it if you want. I don't think most people do so, though.