Public opinion is the outcome of many interrelated forces. The mass media which includes newspapers, radio and television constantly present a flood of information to the public. Thus people are always kept abreast of day to day events. Several people however, may actually be ignorant of the how the government functions, what is the public policy or even what particular issue the candidates stand for. This does not deter them from expressing their opinions. And this gives rise to the source of the formation of public opinion.

Public opinion often depends on the effect of political policies on personal lives. Thus if people are likely to be affected by certain issues, they will respond accordingly. For example, issues related to payments under Medicare or cutting the capital gains tax will evoke a strong response as it is definitely based on self-interest. However all political issues may not personally concern individuals, such as, whether the United States will send more troops to Bosnia?

People may make use of schema or a set of beliefs, to examine a particular subject. It is made up of various influences including one’s background, ideologies and life experience. For example, political affiliation may be regarded as a schema. Thus party preferences are helpful in stabilizing political attitudes. For example a strong Democrat is more likely to come to the conclusion that Democratic candidates are men of integrity and to regard their policy proposals in a favorable light.

People occupying positions of power or responsibility, as in business the church or in labor unions, have immense influence on public opinion. However the greatest weight is attached to the opinions of those exercising control over government, particularly those of the President. The President has as Theodore Roosevelt expressed it a "bully pulpit," with the White House as his platform. Through television he can directly appeal to the public. Further he can summon the Press whenever he wishes, accept invitations to speak in public or arrange for a speaking tour. The President can systematically use press conferences to lead public opinion. Thus President Bush successfully managed to attract a lot of public opinion after Iraq invaded Kuwait in 1990. The President not only gauges and shapes public opinion, but also mobilizes it behind his actions. For example the voters might be influenced by a presidential appeal for support of a civil rights measure in the Congress.