With 14 days to go in the race for the Democratic nomination for mayor, the key factors, according to all camps, are television and radio commercials, televised debates and, last but certainly not least, the endorsement of the editorial page of The Washington Post.

Four years ago, when The Post endorsed Barry, six editorials in the final 14 days of the campaign called for his election. Such a performance from what was then one of two major newspapers in town is widely credited with being a critical factor in Barry's victory.

The fact that the now-defunct Washington Star endorsed then City Council Chairman Sterling Tucker was a so-what in the face of The Post's repeated endorsements of Barry as the candidate who represented a change from what many considered the bureaucratic mess of the Walter Washington years.

The Post endorsement was thought by many to have been particulary crucial to Barry's landslide victory in largely white Ward 3 and his success among white voters in inner city areas such as Foggy Bottom and Capitol Hill. This year, whites in the city appear divided between Barry and his leading opponent in the race, lawyer Patricia Roberts Harris, with Harris having a slight edge.

The feeling this year is that the endorsement could swing those votes and some undecided voters. If that swing is in Barry's favor, it could be all he needs as the front-runner to ensure a victory, the thinking goes. If the endorsement goes to Harris, it could close the gap between her and Barry suggested in the most recent polls.

The Post's editorial page editor, Meg Greenfield, who was the deputy editor when Barry was endorsed in 1978, declined Monday to comment on whether The Post will endorse, and if it does, whom. Since 1978, the paper also has changed publishers. Katharine Graham, the former publisher, is now chairman of the board of The Washington Post Co., the newspaper's parent company. Her son, Donald E. Graham, is now the publisher.

In recent months, the editorial page has broken with its past criticism and supported Barry throughout attacks from many quarters on his handling of the budget. Its only recent criticism of him was when he neither signed nor vetoed no-fault auto insurance legislation, allowing the controversial measure to become law without his signature.

In a letter to the editor last week, candidate John Ray complained that the editorial writers had only recently discovered the election and criticized them for praising a position paper put out by Harris and virtually ignoring similar issues papers he had released months earlier. Ray said the newspaper was preparing to endorse Harris.

"The endorsement will have a big impact no matter how it goes," Ray said later, "it always does. An awful lot of people get their information from The Post. Maryland Gov. Harry Hughes won his race last time when he got the Baltimore paper's endorsement and Marion won here last time because he got the Post endorsement. . . . A lot of people who had questions about him said Barry really must have something going for him if The Post endorsed him."

Charlene Drew Jarvis, the fourth candidate in the race, questioned whether the endorsement could possibly have as much impact this time as it did then.

"It was unfairly done in 1978, that was why it was so decisive," said Jarvis. "It was day after day of the same endorsement. I think Marion has the most to gain again from an endorsement, even if it is done fairly this time, though, because an endorsement always greatly strengthens the incumbent."

For Harris' campaign, the support of the editorial page would be one of the only major endorsements it has won. Most key political activists and ministers have gone with Barry.

"It could be a telling blow if we lost it," said Sharon Pratt Dixon, Harris' campaign director, "but it would not be a killing blow. It really would be a pity though. Marion's house of cards is going to fall no matter what the outcome of this election, and that will hurt the city."

Barry last week downplayed the importance of the endorsement, although he, like the other candidates, has accepted an invitation to lunch with editorial writers and others from the paper.

"Everything counts," he said. "I'm not putting all my political eggs in one basket. We're looking for endorsements from any and everybody we can find. I'd welcome it. But as for what it might mean to get it, I don't want to comment on that."

Barry's campaign manager, Ivanhoe Donaldson, said he would "rather have it the endorsement than not have it," but he says some attach too much value to the 1978 endorsement.

"All endorsements are important," he said. "It was important last time, but it wasn't the key. . . . This time it would mean another tier of support for the mayor from the principal establishment newspaper in town.

"If Marion gets it, it strengthens his consensus," he added. "If Mrs. Harris gets it, it means there is a glitch in the mayor's support. How much of a glitch, no one knows."