Pressure on the governing or other political parties may be exerted by interest groups or opposing parties or factions, whether for political or non-political purposes. The most powerful pressure groups may be financial, highly organized and elitist in inclination. Where vested interest is concerned, much needed reforms may be effectively blocked. Where political representation is becoming more of a group activity than an individual one, the interest of minorities and individuals who are less well organized or less wealthy may be disregarded. Pressure from political groups or parties on non-political matters may provide a barrier to progress and reform by making an emotional issue of complex problems. This may occur on a national or international level. Methods of pressure include propaganda, intimidation, internment, and the use of secret police.
Political influence can be exerted in non-political affairs, and non-political entities can enter into political affairs (as exampled by transnational corporations and religious bodies). Political influence may be gained through the use of propaganda, intimidation or other pressure and may be a function of party or power politics or international conflict (including ideological conflict) for influence over other countries.
Political pressure groups are most noticeable in constitutional democracies. In dictatorships or single-party states they may occur more as factions than distinct groups.
Political pressure groups are intrinsically unequal, either in economic strength or in the degree of organization; and their demands, if met, may discriminate against minorities or individuals. If opposing pressure groups are of equal or near-equal strength they may cause severe social and political conflict which may culminate in anarchy or political and national disintegration.
Vested interest groups have access to the means of decision-making and control it in order to perpetuate their own interests and preserve a static system. In the current era of rapid social change, such groups offer the comfort of familiar approaches and familiar solutions. Disestablished groups are largely disunited and lack access to the tools of the system, limiting effective action.