First described by Burns in 1978, opinion leaders were one of his five types of transactional leaders documented. Opinion leaders are those individuals that are thought to be in touch with the public's attitudes and outlook.
In addition to opinion leaders, the other transactional leaders documented by Burns included the group leaders, legislative leaders, executive leaders, and party leaders. The transactional nature of opinion leaders is akin to a quid pro quo relationship. In exchange for expressing their opinion and gaining their follower's support for a certain individual, that same individual would return the favor to the opinion leader.
For example, the leaders of bargaining units often express their support for a presidential candidate. In doing so, that candidate may receive the votes of the union membership and be elected into office. The hope is the opinion leader's influence will eventually be rewarded by the President through the granting of political favors.