The majority of these correspondents are members of the White House Correspondents' Association. For more than a century, the organization has encouraged its members to properly report on the president and vice president, therefore increasing openness at the highest levels of American government. These reporters are part of a larger group called "White House staff." The staff includes everyone who works within the executive branch but does not include people like teachers or nurses who work for the Department of Defense. There are several positions on the staff, including assistant press secretaries and special assistants to the president. They can hold any level job from intern to presidential appointee. In addition to those who work directly for the White House, there are also journalists who cover the president at large. These reporters often have long-term relationships with particular newspapers or news organizations, so they do not necessarily work for the White House but instead report on it. Some examples include Washington reporters for newspaper chains such as the Denver Post or Chicago Tribune, who cover Congress and the presidency simultaneously. Other examples include reporters who cover politics for television networks like NBC News or CBS News, who also report on the president during election years when his or her job approval rating becomes important. Finally, there are journalists who cover the president solely because he is president. They are usually assigned to cover the White House by a paper or news organization that has no other choice.