Nashville — By all counts, Tennessee politics should be cystal clear. This is the land where political animosities date back at least to the Civil War; where regional divisions are so distinct they are recognized in the state constitution; where the Democratic Party reigns in local politics in most of the state.
But it's not that simple - as the three Democratic presidential candidates, who have toured here in recent days, are finding out. In the run-up to Tuesday's primary, they may find more question marks than clarity.
''We're a border state without a real fixed notion,'' says Rodney Grunes, chairman of the political science department at Southwestern at Memphis. ''Are we mid-South? South? Midwest? . . . We're not here and we're not there. And I think that's part of our problem.''
Some voting patterns have ''more clearly become nondescript,'' adds J.Leiper Freeman, a political science professor at Vanderbilt University, without a hint of contradiction.
The problem is that in some races, everyday, law-abiding Democrats vote Republican. The amount of ticket-splitting, says one observer, ''is incredible.''
In 1982, for example, Tennessee reelected its well-liked Republican governor with 60 percent of the vote; the same year, by a similar margin, a Democrat won a United States Senate seat. Tennessee's other senator, Republican Howard H. Baker Jr., is retiring after three terms - testimony to his popularity here.
In local elections, the state remains majority Democratic. Both houses of the legislature have Democratic majorities.
With the execption of traditionally Republican eastern Tennessee and the Memphis area, Republicans ''don't want to fool with the sheriffs, the local tax assessors,'' explains Susan Richardson-Williams, state chairwoman of the GOP.
Where Republicans have made more inroads is in national elections. In the past eight presidential races, for example, Tennessee voted Republican six times. (The exceptions were Johnson in 1964 and Carter in 1976.)
Even in statewide races, Republicans have done well since the 1960s. They have been helped by a series of bad Democratic candidates, observers say, especially the last Democratic governor, who was convicted for extortion and other crimes.
Slowly, Tennessee appears to be moving toward a stronger Republican Party. But, Professor Freeman says, ''we are about 11/2 of a two-party state.''
Given Tennessee's moderate streak in national elections, one of the most intriguing questions here is how Gary Hart will fare.
Will he get cross-over votes in eastern Tennessee, a moderate Republican stronghold? Will he be able to attract rural voters, concentrated mostly in western Tennessee?
This is not an overwhelmingly Walter Mondale state, observers say. John Glenn would have done well here. Tennessee's US Sen. Jim Sasser (D) lent him important support and has remained neutral since Senator Glenn dropped out of the presidential race.
On the other hand, Hart has big problems with anonymity.
''Hart just isn't known in the rural areas at all,'' says Robert Swansbrough, chairman of the political science department at the University of Tennessee at Chattanooga.
But with a growing number of independents, other candidates like Hart might do well in the future.
''I believe Hart is on the right track when he says there is a change of attitude in the country,'' says Richard Lodge, state Democratic chairman. ''What Gary Hart is trying to be is Congressman (Albert) Gore (Jr. of Tennessee).''
Tennesseeans want candidates that are bright, articulate, and innovative, he says. That's a tradition consistent with the state's moderate brand of national politics.
But Hart does not appear to be able to capitalize on it, Mr. Lodge says. ''It's hard to be a yuppie (young urban professional) in Tennessee.''