I suspect that when this current campaign for the Democratic Party's presidential nomination is over, one episode will stand out above all others in the memory of those who covered the story.
It will be the time when Walter Mondale refused (or was unable) to name any incident or time when he disagreed with the policies of organized labor.
It has been reported that Lane Kirkland, president of the AFL-CIO, who was largely responsible for the organization's early endorsement of the Mondale candidacy, was both astonished and appalled. He has been in politics long enough to know that it is not good for a candidate to be seen to be so totally wedded to a single constituency, even his own.
Sen. Gary Hart has been a substantial beneficiary of that tactical mistake. He has been particularly careful to avoid such commitment to any one group or sectional interest. He scores well among uncommitted voters for having differed from organized labor on several issues, including import restrictions. He also voted against the proposal to bail out Chrysler Corp. in spite of labor support for the bail out.
It must be particularly unnerving for any presidential candidate to go over the American political story and read how often an otherwise promising candidacy has been derailed and even fatally ruined by some such episode, sometimes by only a single fateful sentence.
For example, George Romney had been a successful governor of Michigan and had done well in Washington as secretary of HUD. In 1967, with Lyndon Johnson and the Vietnam war losing popularity, Mr. Romney decided to have a run for the Republican nomination. He came out against the war, although originally having been in favor. He was asked by a reporter why he had changed his mind on the war. He replied that in the beginning he ''had been brainwashed.'' Perhaps it was a pity, but that was the end of the Romney candidacy.
Sen. Edmund Muskie had a respectable chance at the Democratic nomination in 1972. The Democrats almost certainly would have done better under his leadership in that year than they actually did under George McGovern. But in Manchester, N.H., speaking from a flatbed truck in front of the arch Republican Manchester Union, which had just slandered his wife, he showed such emotion that several reporters said that he wept.
Others said that he only brushed snow out of his eyes. Whatever the fact, it was the end of the Muskie candidacy. The lesson was this: No matter what vicious things are said about even his wife, a candidate must not be seen to show deep emotional resentment.
Ronald Reagan in 1980 gave the perfect performance in this respect. He always kept his cool. He always managed to appear to be good humored.
One incident was the affair of the microphone at the high school in Nashua, N.H. A debate had been scheduled by the local newspaper, the Nashua Telegraph, but only between Mr. Reagan and George Bush. Candidate Reagan wanted the four other Republican candidates - Howard Baker, Robert Dole, Philip Crane, and John Anderson - to be allowed to join the debate. The editor and Mr. Bush refused. Mr. Reagan stated firmly, ''I paid for this microphone'' - which indeed he had. The editor and candidate Bush finally agreed to let the four others appear on the stage at the end.
Mr. Reagan came out of that with a reputation both for firmness and for fairness. His candidacy took off. The Bush campaign had been running smoothly until then. It never recovered from what was then called ''the debate over the debate.''
My memory does not bring up any one remark by Thomas Dewey to explain why he lost the 1948 election to Harry Truman - to the surprise of almost everyone but Mr. Truman himself. But Alice Roosevelt Longworth (Teddy's daughter and a lifelong Republican) was widely quoted during the campaign as saying, ''You really have to know Tom Dewey quite well to dislike him.'' It fitted a certain self-satisfaction about Mr. Dewey which could help to explain what happened.