From being a conservative right-winger until the early 1990s, he also became increasingly leftist in his views as far as social policy and globalization are concerned. In 2007, he announced he had become a member of the attac network. This happened weeks before the 2007 G8 summit, which Germany, holding the 2007 G8 presidency, was hosting. Geißler himself said that his joining of attac had to be seen in the context of the upcoming G8 summit.