Glenn's hopes rest with moderates

''I am by far the most liberal of the candidates remaining in this race,'' John Glenn told a group of reporters here. A moment later, Senator Glenn realized he had misspoken. ''I'm sorry,'' he said. ''I'm far more moderate.'' Mr. Glenn, chuckling at his mistake, repeated again: ''Moderate. Moderate.'' Then he spelled it for emphasis: ''M-O-D-E-R-A-T-E.''

It was a lighthearted moment in a campaign that hasn't enjoyed many laughs in the last few weeks. But it also told something about Glenn's strategy as the all-important Super Tuesday draws near.

By convincing the voters of Florida, Georgia, and Alabama that he is the only true moderate left in this race, Glenn hopes to pull off an upset as big as Gary Hart's victory in New Hampshire.

Southern Democrats, after all, are known for their moderate-to-conservative views. They're the ones who voted for a Dixiecrat candidate in 1948. And they backed Gov. George C. Wallace, Alabama's champion of segregation, in all of his presidential forays.

Dixie politics has moved closer to the center in recent years. But it is still much more ''moderate,'' to use Glenn's adjective, than most of the country.

Political analysts say Glenn's best hope for an upset will probably come in Alabama. It's the most conservative of the three states. And Walter Mondale, long seen as Glenn's greatest rival in this region, is believed to be weaker there than in Georgia or Florida.

A huge number of Dixie voters - perhaps half of them - remain undecided. This is Glenn's opportunity. But in all three Southern states, Glenn is in danger from the sudden rise of Gary Hart. Pollsters say that a number of voters who don't want to go with Mr. Mondale have been gravitating in recent days toward Senator Hart as the strongest alternative.

Why aren't more people drawn to Glenn?

Claiborne Darden Jr., a veteran Southern pollster, says that there are only three things that really count for much in politics: emotion, emotion, and emotion.

Despite his colorful background as astronaut, Marine pilot, and US senator, Glenn comes across to Southern audiences as rather bland. ''John Glenn has not been able to stimulate emotion at all,'' Mr. Darden says.

A Democratic county chairman from rural south Georgia, where Glenn hopes to score heavily next Tuesday, complains that the senator's campaigning is ''colorless.'' Another Georgia county chairman says Glenn's style is simply ''dull.''

Glenn's staff is aware of this perception. Staff members say he is at his best when he gets fired up about the things he deeply believes in. That's the Glenn they think could pull an upset in the South.

At a press conference here, Glenn showed that kind of spark only once, when he was asked why he was going into debt for what looked like a losing cause.

''I borrowed money because I believe in what I'm doing. . . . I've devoted my life to this country. . . . I see some of this American dream being cut back by economic policies and foreign policies and educational policies and research policies that I think are wrong. . . .

Glenn strategists hope they can get the message across that he is the only one who combines the best of the other candidates. Mondale talks of experience. Hart talks of new ideas.

''Glenn has both. He merges those two - the experience, and the view toward the future,'' an aide says.

Next Tuesday, Glenn must do well enough to at least hang on, to continue as a candidate who will be taken seriously. Already, the number of reporters following his campaign has dropped. As a result, the candidate has switched from a four-engined Lockheed Electra to a smaller, two-engined Convair turboprop.

It's difficult for the Glenn team to look at the polls (Hart rising fast, Glenn dropping) without wincing. ''We kick ourselves every day,'' a Glenn adviser says. ''If we hadn't finished fifth in Iowa, it might be different now. We got in Iowa late. . . . We weren't organized.''

Before Iowa, Glenn's private polls showed he had moved to within eight points of first place in New Hampshire. After Iowa, the bubble burst.