I'm pretty sure this is [Greenplace][1] by Tom Purdom. Many things match but some do not.

It starts with the protagonist being placed in a wheelchair by a large bodyguard. He then injects himself with a red (not blue) liquid.  The bodyguard pushes him around the neighborhood and the inhabitants are hostile.

It ends

> This campaign was going to be worse. He could imagine the efforts the
> Boyd organization would make to control the minds of himself and his
> friends. They would attack his psyche with every weapon in the modern
> arsenal.  As plainly as it were a drama projected on a screen, he
> could see the psych technicians maneuvering across the Eighth
> Congressional District...

It was in the [1965 World's Best Science Fiction][2] Carr and Wollheim collection.

You can read it online in the Internet Archive [here][3].


  [1]: http://www.isfdb.org/cgi-bin/title.cgi?58813
  [2]: http://www.isfdb.org/cgi-bin/pl.cgi?50538
  [3]: https://archive.org/details/Fantasy_Science_Fiction_v027n05_1964-11_PDF/page/n1/mode/2up