Officers

Hi, what is "officers" in this context?

" Such links are often developed through participation in joint ventures with other interest groups in the pursuit of specific mutual political objectives. This activity enhances their leadership mandate and reinforces the status of the interest body representing the specific segment of society. David Kwavnick pointed out in his study, Organized Labour and Pressure Groups, the Canadian Labour Congress 195658, that relations between the Canadian Labour Congress and Canadian political leaders clearly demonstrate that the principal officers of the former, particularly its president, have access to any member of the cabinet, including the Prime Minister, at almost any time for the discussion of virtually any aspect of government policy."