From Longman Dictionary of Contemporary Englishbalance of powerˌbalance of ˈpower noun [singular] PMa situation in which political or military strength is shared evenly The election of so many Republicans to Congress has changed the balance of power in Washington. A small centre party holds the balance of power (=is able to make either side more powerful than the other by supporting them) in the Assembly.
Examples from the Corpus
balance of power• The process of economic development was accompanied by a balance of power between the crown and the landed nobility.• There was a balance of power - but there had always been a balance of power.• Case said these seemingly contradictory deals were simple exercises in economic balance of power.• In the years that followed, achievements by one side or the other alternated, maintaining a precarious balance of power.• The crisis changed the balance of power among the participants in the transformation process.• The incident was a small measure of how the balance of power, and relevance, within Virgin had shifted.• That decision shifted the balance of power away from Wall Street specialists. 