In one of the early books on liberal TV news bias, The News Twisters (1971), author Edith Efron recounted that in the November 4, 1970 edition of Variety, although Walter Cronkite "conceded he was a 'true liberal,' he defined the position as having no content at all: a liberal, said Mr. Cronkite, was one who is 'not bound by doctrines or committed to a point of view in advance.'"
Efron also recalled the November 25, 1969 broadcast of 60 Minutes, in which Cronkite defended CBS against charges of liberal bias from Vice President Spiro Agnew:
Well, we all have our prejudices, we all have our biases, we have a structural problem in writing a news story or presenting it on television as to time and length, position in the paper, position on the news broadcast. These things are all going to be affected by our own beliefs, of course they are. But we are professional journalists. This is the difference. We are trying to reach an objective state, we are trying to be objective. We have been taught from the day we went to school, when we began to know we wanted to be journalists, integrity, truth, honesty, and a definite attempt to be objective. We try to present the news as objectively as possible, whether we like it or don't like it. Now that is objective.
Efron summed up that Cronkite merely ended up saying "Objectivity is when one tries to be objective." That's a little like saying that victory in war is when one tries to win.
