Why does Tocqueville believe that "the farther electoral rights are extended, the more is felt the need of extending them"?

Tocqueville was a historian, political scientist, philosopher and politician who wrote a great book called Democracy in America. He believed that the farther electoral rights were extended, greater was the need of extending them. Tocqueville justified that by saying that the strength of democracy increases after each concession and after each concession the demands increase, as well.