Four men armed with wooden sticks bashed him up around 12.30am Monday after witnessing him remove a 1Malaysia flag hung up at the area.
Penang police spokesman (general election) Asst Comm Roslee Chik said the victim sustained serious injuries and received 20 stitches and also a fracture in his face.
He was warded at the Penang Hospital and is still unconscious.
ACP Roslee said the case was being investigated under Section 148 of the Penal Code for rioting.
"We want to advise the public not to fight as we want to ensure that this round of elections is a peaceful one," he added.