and, also, let me be clear on this point.

the invasion of afghanistan was intended to be a long term occupation of a strategically vital region in the centre of asia. there is no goal to be completed in afghanistan, no end point, no exit strategy. but, that is not a reason to send troops home, but the very reason they are in the first place. so, there will be no withdrawal from afghanistan. ever. you'd might as well be talking about withdrawing from japan or korea, things that will not happen until the empire starts to permanently crumble. as the withdrawal of legions from the frontier in britain marked the end of roman control in the northwest, symbolically if not functionally, an american withdrawal from afghanistan would actually signal that the empire is beyond permanent decline and at the point of imminent collapse.

when candidates start talking about sending troops back from afghanistan at this stage in the process, there's one of two reasons:

1) they have not yet been briefed, and they essentially have little understanding of the actual goals and purposes of american foreign policy. when candidates like this win (and while obama was a candidate of this type, let's recall that he actually ran on bombing afghanistan, not withdrawing from it. his argument against iraq was that it redirected resources away from afghanistan (which is probably wrong, too)), they usually change their tune very quickly.
2) they're deep state and are playing right into the propaganda. and, they're lying through their teeth about it.