Washington — Walter Mondale did better than expected in the first presidential debate. Here's what political insiders say that means:
* Mr. Mondale's campaign, which had been sinking fast, should find fresh energy. His workers will be encouraged. His rallies should be bigger.
* The polls could start getting a little better for Mondale - or at least stop getting worse. On Sunday, the day of the debate, a CBS-New York Times poll reported Mondale 23 points behind.
* Other Democrats, running in tight Senate or House races, should be helped. Even if Mondale loses, they may avoid getting pulled under with him if he can narrow the gap to about 10 points.
* Press coverage may improve. Many stories have been concentrating on Mondale's poor crowds, weak organization, and discouraging polls. Mondale looks tougher now.
* President Reagan handed Mondale some political ammunition. Mr. Reagan's reluctance to spell out what he will do in his second term could become a focus of Mondale campaign ads.
There will also be an impact on Reagan and his campaign team. More hard work needs to be done to get the President ready for the second debate, which will concentrate on foreign policy, on Oct. 21, insiders say. One analyst suggests this probably means ''no more weekends off'' for the Reagan staff.
Stephen Hess, an analyst at the Brookings Institution, says the impact of this debate may not yet be fully apparent. Says Mr. Hess:
''We judge debates almost aesthetically, rather than politically. Mondale won the debate by some sort of aesthetic scale. We heard him loud and clear, and we now know his message.''
At the same time, Hess says, those who heard Mondale talk about higher taxes and deficits may judge him to be ''out of phase with the country.'' Mondale may have won, but in the end it ''may be a real Pyrrhic victory.''
Nelson Polsby, a political scientist at the University of California (Berkeley), says that a rule seems to be developing about debates: an incumbent like Reagan, or Jimmy Carter in 1980, ''should never debate. They always lose.''
The situation is stacked against the President. The two men appear with ''the same suit, the same haircut, they get approximately equal time, and they are addressed equally.'' The whole situation puts the challenger up on a pedestal next to the President, and this takes away some of the incumbent's aura.
Professor Polsby says that in addition to all this, Mondale performed exceptionally well. He even managed to use informal touches, such as his reference to Will Rogers, better than the President, who is usually very good at that. Reagan had no equally memorable lines.
In addition, Reagan allowed himself to be pulled along by Mondale's agenda. Much of the debate centered on economic numbers like the $172 billion federal deficit, not declining inflation or interest rates.
Mervin Field, another California Reagan-watcher, thought Mondale's tactics were ''very effective.'' But he says the major impact of the debate was probably to ''reinforce existing dispositions.'' There was little in Mondale's presentation to win converts from the ranks of Republicans or independents. His appeal was aimed right at people already leaning to Mondale.
An ABC News poll of just over 600 voters who watched the debate supports Mr. Field's statement. It found that, by a 39-to-38 margin, they thought Mondale had ''won'' the debate. But only 2 or 3 percent of them thought it might make them switch to Mondale.
A Democratic insider privy to Mondale strategy said that one of Mondale's most effective tactics was to speak in praise of Reagan, as a person.
''I like President Reagan. This is not personal,'' Mondale said. At another point, Mondale lauded Reagan for raising America's morale. He also thanked Reagan for being willing to debate.
This effort to separate Reagan, the man, from Reagan and the issues was intentional - the result of a strategy session among Mondale planners last week. The idea of praising Reagan was first greeted with derision by some Mondale planners, according to one of those present at the meeting. But the idea was eventually accepted. Afterward, a number of analysts said the tactic was extremely effective, and threw Reagan off his stride.
While Mondale did better than par, Reagan did not. Several experts said his answers were too defensive, too full of numbers, convoluted, and lacked down-to-earth touches.
Even so, Reagan was effective in several ways. He was clear on opposing taxes. He handled the abortion question deftly. And - perhaps most important - he avoided any major gaffes. When you are 20 points ahead, that's the top priority.
Some experts suggested that Mondale's performance won't pull him close to Reagan, but it could at least make it more of a contest. Professor Polsby notes that Mondale is currently doing better than George McGovern did in 1972, but not quite so well as Hubert H. Humphrey in 1968.
If Mondale can narrow Reagan's lead, the most important benefit for Democrats could be felt in close Senate races such as Illinois, Iowa, and North Carolina.