Sixty-year-old Carol Kreck, a former reporter for The Denver Post held a sign that read "McCain=Bush' Monday when police removed her from the atrium of the Denver Performing Arts Complex.
She says she was removed as she asked an officer whether he could deny her free-speech rights by taking away her sign, while McCain supporters wore buttons inside the venue.
Jenny Schiavone, a spokeswoman for the performing arts center, says the venue is city-owned rental property but is not legally defined as private property.
Police spokesman John White say officers acted as they would have for any complaint on private property.
McCain campaign spokesman Tom Kise says the town hall was open to supporters and opponents.