Jesse Jackson holds the only wild card in Maryland contest

The long wharf is empty. Its unloading cranes - which resemble giant steel camels - are still. ''I been here 10 years,'' says Roman Pedzich, a longshoreman here at Baltimore's Dundalk Marine Terminal. ''I only work two, three days a month.''

Maryland's primary is but a week away, and Gary Hart has just made a quick campaign stop at this wharf, to dramatize his call for increased American exports.

Mr. Pedzich and his co-worker, David Geleta, say they like what Senator Hart is saying. ''International trade,'' sighs Mr. Geleta. ''That's a big thing. We're not shipping enough out.''

But they hedge about who they'll vote for - and only a handful of workers showed up to hear Hart.

Hart scored strongly in Maryland in polls taken after his New Hampshire primary victory. But he has faded in the stretch, and Walter Mondale is now a strong favorite in the state's May 8 primary contest.

In some ways, Maryland is the primary that national politics forgot. The 42 delegates that will be chosen here next week seem a small prize next to the 154 at stake in Ohio, the same day. The large states of Indiana and North Carolina also have primaries May 8; on May 5, Texas caucuses will choose 169 delegates.

Hart, for instance, has spent little time in Maryland. His Dundalk appearance was an hour-long stop in a day that took him from Indiana to Texas.

Though Maryland Democrats are occasionally overcome by a desire to vote independently (George C. Wallace won the Democratic primary here in 1972; Edmund G. Brown Jr.triumphed in '76), for the most part it is a place where the party of Franklin D. Roosevelt still lives.

''Maryland is very much an old-line Democratic state,'' says Eric Uslaner, an associate professor of government at the University of Maryland. ''It has all the demographic characteristics of a Mondale state.''

About 20 percent of the state's people live in Baltimore. Slightly over half of this urban population is black. Most other Marylanders live in suburbs: Baltimore County, a blue-collar area; Prince George's, a middle-income, one-third black county; and Montgomery County, a diamond crust of rich liberals.

Maryland also has the ''eastern shore,'' an area between Delaware and the Chesapeake Bay whose politics and atmosphere are that of the rural South. The state's western panhandle is populated by farmers who consistently vote Republican.

''Maryland has little pieces of almost all of America,'' notes Dr. Milton Cummings, a political science professor at Johns Hopkins University.

Walter Mondale's approach in Maryland is itself textbook old-fashioned politics. First, get the endorsement of every prominent Democrat you can find. Then appear often in public with their arms around your shoulders.

Mr. Mondale's allies here include Gov. Harry Hughes, Sen. Paul Sarbanes (state campaign chairman), Baltimore Mayor William Schaefer, and Rep. Parren Mitchell, Maryland's most prominent black politician.

The approach seems to be paying off. Political scientists and the state's most prominent columnists are putting their money on Mondale. His own polls show him comfortably ahead.

''Things look promising,'' chortles lawyer Brian Barkley, a Mondale delegate candidate in Montgomery County.

The Hart campaign, as all across the country, is relying in Maryland on shoe leather and youth. ''Our strategy is 'door to door,' '' Gary Green, Hart's state press secretary, says. ''We have 2,500 volunteers out every day, knocking on doors. We're running strong.''

An early spring poll by the University of Maryland found Hart leading Mondale. He has since slipped. Observers say Hart has not been able to capitalize on his natural appeal in Montgomery Country, an area full of Audi sedans, French cheese stores, and young professionals.

Milton Cummings of Johns Hopkins University notes that Montgomery has more federal workers than most ''Yuppie'' (young professional) areas, and that candidates often find it politically perverse.

Jesse Jackson, however, is the biggest variable in the Maryland contest. Observers say he has a chance to finish second. Officials from rival campaigns say privately they expect Mr. Jackson to win Baltimore; with a large black turnout, he could also take Prince George's County. Overall, say Jackson officials, they have signed up at least 25,000 new black voters.

''Maryland was not a key state for any other candidate. We made it a key state for Jackson,'' says Sherman Roberson, Jackson's Maryland coordinator.