St. Louis — With the Pennsylvania and New York primaries behind them, the three Democratic hopefuls are looking to the big contest of Texas and California. Before their campaign wagons reach there, however, all three face the April 18 caucuses in Missouri - a state that, in the words of one fresh-fish farmer from the Ozark region, ''is kind of in the middle.''
In fact, Missourians find themselves in the middle of a lot of things.
''We're a real meeting ground for a lot of cultures,'' says Terry Jones, dean of the College of Arts and Sciences at the University of Missouri at St. Louis.
For example, this is a state where East meets West. Missouri's pioneers founded the last great city in the East (St. Louis) and the first large city in the West (Kansas City).
This is also where North meets South. Farmers in the northern third of the state harvest Midwestern farmland. Those in the southeastern portion, known as the Boot Heel, work cotton fields reminiscent of the South.
''It's a Northern state with Southern mores,'' says Charles L. Bussey Jr., state campaign chairman for the Rev. Jesse Jackson. ''Missouri never quite knew whether it was 'slave' or 'free' (in the Civil War).''
Even the political geography is a patchwork quilt. The City of St. Louis has a strong labor and Democratic Party tradition. Like many other frost-belt metropolises, it is contending with classic urban decay - the city lost 27.2 percent of its population between 1970 and 1980. The rural areas range from central and northeastern Missouri - called ''Little Dixie'' because they were settled by Southerners who became conservative Democrats - to the southwest portion, which is dominated by backwoods Republicans who migrated from Kentucky, eastern Tennessee, and West Virginia.
So Missouri really represents a kind of uneven political terrain in which each candidate should be able to find a constituency tucked away somewhere.
To do well here, the Democratic presidential hopefuls will have to mobilize the state's Democratic strongholds: St. Louis, northern St. Louis County (the county and city are separate entities), Kansas City, and the Boot Heel.
Who will win here?
According to political observers, Missouri is Walter Mondale country.
''Missouri went for Mondale early and hard,'' says George D. Wendel, director of the Center for Urban Programs at St. Louis University.
Despite his denial here on Wednesday that he was the front-runner, Mr. Mondale is expected to receive the largest share of the 86 delegates at stake here.
There are many reasons.
Missouri Sen. Thomas Eagleton, a personal friend of Mondale's, is campaigning very actively for him. The state's caucus system, which requires careful organization, is better suited to the long-organized Mondale campaign. He should do well with St. Louis's strong labor and Democratic Party support. Meanwhile, rural voters who backed Sen. John Glenn when he was still in the race appear lukewarm to overtures by Sen. Gary Hart or Jesse Jackson.
''Glenn has withdrawn, leaving some of those people without a candidate,'' says David Leuthold, political science professor at the University of Missouri at Columbia. There has been some talk of sending uncommitted delegates from certain regions, he adds.
Missouri will be a test to see if Mondale can broaden his appeal among voters and if Mr. Hart can attract votes in Kansas City because of his Western roots. (He was born in the neighboring state of Kansas.)
Mr. Jackson, meanwhile, seems assured of capturing the large black vote in the state's two major urban centers. He has received endorsements from black leaders in St. Louis, which is 46 percent black, and Kansas City, which is 27 percent black. Some organizing efforts are also going on in the heavily black Boot Heel.
The problem, Mr. Wendel explains, is that the state's caucus system has a 20 percent threshold rule, which could hurt Jackson in areas where his supporters fail to generate 20 percent of the vote.
Still, Jackson's chairman here, Mr. Bussey, expects his candidate to pick up 8 to 10 delegates.