Answer:
Political parties give power to the citizens when they join the interests of many individuals and social groups in the political arena. They take power away from the citizens when they become corporations mostly interested in preserving their own power.
Corporations and lobbysts take power away from citizens when they pool money to politicians in order to influence policy.
Media takes power away from citizens when they become biased and push agendas. They give power to the citizens when they deliver objective and important information to the public. The same is true for internet companies.
Finally, other politicians and former government officials take power away from citizens whey they use their political power to influence policy in an unfair manner. They do the opposite (give power to the citizens), when they influence policy in a fair manner.
How does this limit the power of the people to keep politicians and government accountable?
The influence of these interest groups can lead policies in ways that are not agreed upon by the citizens. In other words, these interest groups can subvert democracy, making citizens feel that their votes and opinions do not matter.