There was something missing yesterday when the Dodge and Ford pickups driven by the boys from the "Fightin' 28th" moved across the rainslicked roads of southern Prince George's County in a traditional campaign caravan for the local Democrats.

Plastered on the sides of the big-wheeled trucks were billboards and bumper stickers promoting the election campaigns of many familiar Democratic politicians in the county - Miller and Wolfgang and Vallario and McCaffrey and Mills and Francois and Hartlove and Marshall and Aluisi.

But nowhere in sight were the green-and-white "Kelly" stickers.

Although counting bumper stickers is by no means an accurate method of predicting an election result, the fact that a Democratic caravan would so noticeably exclude the name of the incumbent Democratic county executive says something about the problems Winfield M. Kelly Jr. has had this fall in this race against Republican Lawrence J. Hogan.

Kelly was less active, appearing personally at only two of the eight shopping centers that his caravan visited. His campaign workers passed out reproductions of various newspaper endorsements Kelly had received, including both major weeklies in the county - the Journal and the Sentinel - and The Washington Star; the newspaper with the largest circulation in the county.

The Star endorsement, which appeared in Saturday's editions, said Hogan had not "made a persuasive case against a second term for Mr. Kelly - and that is the requirement for a challenger." Friday, The Washington Post endorsed Hogan. The Post said Hogan was better qualified to accelerate the integration of the predominantly white police force because he was a conservative and a former FBI agent, and that he was an "energetic new force" unencumbered by "the Democratic/business coalition" that dominates county politics.

The one thing that both candidates seem to agree on is that Kelly must have a high turnout to win. "Usually, a low turnout helps the dominant party, but this is not a usual year," said McDonough. "We have to really take advantage of the 3-to-1 Democratic edge in registration, we have to get after the kind of people who might go to Midas Muffler for the afternoon and forget to vote."

The way Kelly and Hogan have been going at each other since early September, it would be only natural that their election be decided - as both men believe it will be - by one or two percentage points.

Kelly, the 42-year-old self-made millionaire, and Hogan, the 50 year-old former FBI agent and public relations man, have aggressive personalities that become even sharper when they appear in the same room. They have disagreed on just about everything, matters large and small, from the name of an old movie theater in Riverdale to the amount of a surplus in the 1979 budget.

"It's a remarkable chemistry," said William Meyers, a prominent Prince George's attorney who went to grammar school with Hogan but now is one of Kelly's advisers. "Those two little Irishmen can't stand it when one of them gets a leg up."

This competitive nature was in evidence yesterday. Both candidates had scheduled separate campaign tours of the social centers of the county - shopping centers. When Kelly discovered what shopping centers Hogan was visiting, he rearranged his schedule at the last minute to make sure he got to them first.

"We wanted to have a sea of Kelly stickers waiting for Hogan at every stop," said one campaign aide.

Hogan who has a reputation as the most polished campaigner Prince George's has seen, toured the shopping centers in a caravan that included a doubled-decker bus, a fire engine, a calliope, four clowns and J. Glenn Beall, the Republican gubernatorial candidate. Only Beall appeared out of place, often standing alone and muttering "What do we do now?" as Hogan plunged into barber shops, liquor stores, banks, Western Autos, Kresges and other shops.

The red-vested Hogan carried four types of campaign buttons in his pocket - "Hogan," "Italians for Hogan," "Germans for Hogan" and "Democrats for Hogan." The most popular of the four was "Democrats for Hogan."

Kelley was less active, appearing personally at only two of the eight shopping centers that his caravan visited. His campaign workers passed out reproductions of various newspaper endorsements Kelly had received, including both major weeklies in the county - the Journal and the Sentinel - and the Washington Star, the newspaper with the largest circulation in the country.

The Star endorsement, which appeared in Saturday's editions, said that Hogan had not "made a persuasive case agaisnt a second term for Mr. Kelly - and that is the requirement for a challenger." Friday, The Washington Post endorsed Hogan, The Post, said Hogan was better qualified to accelerate the integration of the predominantly white police force because he was a conservative and a former FBI agent, and that he has an "energetic new force" under cumbered by "the Democratic/business coalition" that dominates county politics.