The Democrat party. Popular cartoonists’ symbol, the donkey.
WRONG!
The "cartoonist" (Thomas Nast) was lampooning Andrew Jackson:
"A Live Jackass Kicking a Dead Lion" by Thomas Nast. Harper's Weekly, January 19, 1870.
Somehow the RATs didn't mind being referenced as "jackasses" and only recently threw Andrew Jackass under the bus for being, well...what he was.