“Same shit, different asshole(s)” means that no matter who gets elected, it’s still the same bad stuff. A saying in similar form is “same shit, different day.”
 
“Same shit, different asshole” has been cited in print since at least 1998. The saying became popularized in 2004, when posters compared George W. Bush to Adolf Hitler.
   
 
Urban Dictionary
Same shit, different assholes
When you expect things to be better with a new person and they turn out not to be. Usually the person is a politician, a new boss, or a new boyfriend.
“So much for the promised change. I was sure Obama would be the one.”
“Oh well. Same shit, different assholes…”
by petetoth Jan 5, 2010
 
Google Books
Like Being Killed
By Ellen Miller
New York, NY: Dutton
1998
Pg. 216:
Here I go again. Same shit, different asshole.
           
Fool’s Gold
Edman
07/22/04, 17:12:55
Same shit, different asshole
Click here to read George W Bush and the 14 points of facism: ...
 
Google Books
Unhinged:
Exposing liberals gone wild
By Michelle Malkin
Washington, DC: Regnery Pub.; Lanham, MD: Distributed to the trade by National Book Network
2005
Pg. 143:
Rocker Ozzy Osbourne, for example, opened at least one concert with the song “War Pigs,” featuring a video montage comparing Bush to Hitler along with the caption: “Same shit, different asshole.”
 
Google Books
Waking with Enemies
By Eric Jerome Dickey
New York, NY: Dutton
2007
Pg. ?:
The T-shirt next to that sacrilegious message had a picture of Adolf Hitler on one side and President Bush on the other: SAME SHIT DIFFERENT ASSHOLE.
   
Google Books
Psalms of the Pharaoh
By Christopher Alexander Berg
Terrace, BC: CCB Pub.
2010
Pg. 381:
SSDA ( Same Shit Different Asshole )
Palin’s no different than Bush or Clinton…
 
Google Books
Only the Brave
By Peter Pollard
Dorrance Publishing Co.
2011
Pg. 98: 
“Same shit, different assholes,” he muttered.