WHAT has happened to Mondale? News commentators keep asking this question because his last weeks of campaigning are so unspectacular. The question is put in different ways, but it boils down to ''What's happened to Walter Mondale?''
Well, nothing has happened to him. People just keep wishing something would happen, but he keeps on being the same old Walter. The voters had the same problem with Gary Hart when he was winning. He kept turning out more and more like Gary Hart all the time.
What it comes down to is that Democrats simply don't like their own candidates. And it looks as if the indecision is going to continue right on into the fall. Democrats began this election year with high hopes of finding someone of presidential timber. At least they have succeeded half way and have got the timber part.
In spite of Jesse Jackson's mellifluous preachment to blacks, Walter Mondale's pedantic promises to factional groups, and Gary Hart's metronomic, Kennedyesque gesturing to lost liberals, the only real way they can be distinguished is by their hairstyles.
Experts point out that this is going to be a horse race right down to the finish line. However, the people have all gone home and the stadium is empty.
Perhaps the hardest thing of all to explain is the whimsical process Democrats use to select a candidate. In the early part of the race the polls showed that the only candidate who could beat Ronald Reagan in a national election was John Glenn. So Democrats went to extraordinary lengths to vote for someone else. John Glenn was too dull, according to Democratic standards. But dull as compared with what?
Now there is essentially Walter Mondale. The worst thing, it seems, that can be said about him is that he is identified with the Carter administration.
It is also the best thing that can be said about him.
Meanwhile, President Reagan stays at home. He sees no reason to get down and run in an empty arena.