How to align vertex selection to an edge/vert? TL;DR: how do I get my vert selection to align so that the two circled verts align in the Z axis?
edit: to make my question clearer, I'm looking to move all of the selected verts such that the two circled verts are aligned in the z-axis. I know several ways to get just the circled verts to line up.  What I need is to get the entire selection to align with the bottom of the object so that it's suitable for 3D printing.

Here's a super quick and dirty version of what I'm looking to do:

I've been searching through various snap modes and nothing really seems to work.  All of the tutorials that I've found assume you are aligning separate objects, not a selection of verts to other edges/verts in the same object in edit mode.
I've tried messing around with moving the cursor around since I assume that you have to inform Blender which of the selected verts should be treated as the origin of the selection but that has also failed to work. I'm not very familiar with manipulating the cursor though and it's likely I'm doing it wrong.  I have a hard time believing Blender doesn't have a way of doing this since this is a pretty obvious operation with mesh manipulation
You can use Vertex snapping set to Active.

Select all the vertices you want to move
Make the aligning vertex active (white), by clicking it on/off while holding shift
Set snapping to Vertex &gt; Active
Move cursor over the target vertex