THE Hart-Mondale struggle for the Democratic nomination begins to resemble a close-fought, championship tennis match. In the latest set - the Connecticut primary - Gary Hart aced Walter Mondale with surprising ease.
Each candidate now has shown himself capable of coming back strongly after an earlier defeat.
Mr. Mondale, who was trounced in New Hampshire, Maine, Massachusetts, and Rhode Island, got his second wind in Michigan and Illinois.
Senator Hart, drubbed in nine straight primaries and caucuses, mopped his brow, gripped his racket tightly, and blew the ball past a startled Mr. Mondale in Connecticut. The final vote: 53 percent for Hart, 29 percent for Mondale, 12 percent for Jesse Jackson.
The next big match, the New York primary on April 3, could be the pivotal one. While it is expected to be close, the experts say it looks like ''advantage , Mr. Mondale.''
The Connecticut victory for the senator from Colorado was not entirely a surprise, though the margin of his win was greater than expected. The game was played on Hart's kind of court, a state with lots of well-educated, prosperous voters.
''I love it,'' a beaming Hart said afterwards.
What does Connecticut tell us about the next primaries?
Analysts say the data from the first month of voting in the East, Midwest, and South offer clues about why the initiative in this race shifts back and forth.
Many factors play a role. The news media, for example, had a burst of negative tone prior to Illinois and probably hurt Hart.
But perhaps the most critical element is simply old-fashioned demographics. If there are more Hart-type voters in a state, Hart wins. If there are more Mondale-type voters, Mondale wins.
Here's one example:
Exit polls have shown that low-income voters usually prefer Mondale over Hart. High-income voters feel just the opposite. Exit surveys taken by ABC-TV show that in Illinois, 26 percent of the voters came from families with incomes under $10,000 a year. Mondale won solidly there.
It's been the same story in other states where Mondale won. In Alabama, the under-$10,000 category made up 26 percent of the voters. In Georgia, another Mondale state, they were 23 percent.
Now look at Connecticut, Massachusetts, and Rhode Island - solid Hart states. The under-$10,000 group made up only 10 percent of the voters in Connecticut, 13 percent in Massachusetts, 14 percent in Rhode Island.
In Connecticut, voters making more than $40,000 a year (strongly for Hart) made up 27 percent of the electorate. In Illinois (a Mondale state), they were only 17 percent.
Another useful indicator is the way voters describe themselves politically.
Hart has won the primaries in every state where approximately 40 percent or more of the Democratic voters described themselves as ''liberal.'' Mondale has won in every primary (except Florida) where the self-described liberals fell below the 40-percent range.
This tells us, of course, that Mondale is running best among moderates and conservatives. Hart has courted voters across the spectrum, but has done best with middle- and upper-income liberals.
One final indicator: Mondale runs strongest where people have been hit hardest by the recent recession. Hart shines where there is little joblessness. Connecticut has enjoyed the lowest unemployment rate (5.3 percent) in the nation.
All of this tells us that New York could be close, but that Mondale should have the upper hand. New York has regions that were badly affected by the recession. In some areas there's still over 14 percent unemployment. The jobless rate statewide (8.1 percent) is well above Connecticut. And New York has a large pool of low-income voters.
Pre-election polls in New York are currently giving the edge to Mondale. A survey by USA Today gave Mondale a seven-point lead at the beginning of the week.
Daily tracking polls by ABC-TV indicate Mondale's margin may have grown to 10 percent by midweek.