To win democratic elections that are not fully subsidized by the government, nonwealthy candidates must be supported by wealthy patrons. This makes plausible the belief that these candidates will compromise their views to win that support. But since the wealthy are dispersed among the various political parties in roughly equal proportion to their percentage in the overall population, this belief is false.
The argument is vulnerable to criticism on the grounds that it fails to consider that in democracies, government-subsidized elections ensure that the views expressed by the people who run for office might not be overly influenced by the opinions of the wealthiest people in those countries.