Is this wall load bearing based on the attached blueprints?
EDIT: On second look, the drawing actually tells us.  There's a note box to the right: TYP BEARING WALL 2x4 stud 16" O.C. on Continuous footing.  The dashed line around the wall indicates the footing.

ORIGINAL:
If I'm reading the drawing correctly, IT DEFINITELY IS.

For the sake of this discussion, north is the top of the drawing.

There appears to be a beam running E-W from the post to the East wall.  There are no notes on the west wall talking about a beam pocket.  This leads me to believe that the dark line following the same path as the beam is simply a dimension line, not a continuation of the beam.  So the beam does not extend westward towards the area you want to deal with.

This makes the total span in the area you're looking at 36 feet.  Far too long for 2 x 12's,
which means the wall you want to remove is definitely supporting the joists.

Even if the beam does continue, I would take great care. 20 feet is about the max for a joist span.  This job calls for a professional engineer to assess the situation.

The solution is probably to dig a footer where the doorway is now, and put up a steel post and raise another short steel or paralam beam where the wall is.

This involves building temporary stud walls on either side of the existing wall to support the load while you're working.  You'll need to find a contractor who has done this type of work before.