The Diploma thesis concerns itself with the possibilities of election campaigns and their impacts on public opinion on the occasion of the first direct election of the president of the Czech republic. Influencing of the public opinion takes place in a system of public - politics - media, which is described in this thesis. Utilising this system I am going to answer the following question - how effective are election campaigns in influencing election decisions of voters? The witnessed election campaigns were unique in many aspects - they triggered an unprecedented response from the public and the media, which came close to resemble election behaviour in the United States of America, whose presidential election campaigns are considered a classic example. The theoretical background serves the purpose of analysing the election campaign of Karel Schwarzenberg, who, using an online campaign, achieved a result, which surprised a number of agencies examining voters' preferences, and proved, what a good campaign team is capable of given their candidate has strong public support. Next I am going to present assessments of the campaign by political scientists, social scientists and others. Key words: Public, public opinion, possibilities of influencing public opinion, massmedia, election campaigns, american...