IN the 1988 presidential election the South will again be a key battleground. The ``Super Tuesday'' vote reminds us anew of the immense political changes there over the last quarter-century. The South has been the setting for the two most consequential electoral shifts in the United States since the New Deal: The ending of the restrictions that for so long kept blacks from voting and the realignment of black voters into Democratic ranks; and on the other side the movement of a large segment of the Southern white electorate further away from the national Democratic Party. The effects of both developments were evident March 8.
Jesse Jackson, who began his political career in the Southern civil rights protests, solidified his position on Super Tuesday as a figure in Democratic presidential politics. He did this by winning more than 90 percent of the black vote, which made up one-quarter of the entire Democratic primary vote March 8.
The size of the black vote in the South today and the near-unanimity with which it belongs to the Democrats present Southern Republicans with a major problem. In much of the region they must carry the white vote by nearly 2 to 1 if they are to win statewide elections. This is not easy to do, as the 1986 US Senate races attested. In Alabama, Georgia, Louisiana, and North Carolina, Democratic candidates swept to victory in November 1986 on the basis of overwhelming majorities among blacks, with only minority support among whites.
In presidential elections, however, the Democrats' base among whites has been so strikingly eroded that they find it hard to win even with a large margin from the black community. Surveys taken by CBS News and the New York Times on Super Tuesday found only 44 percent of those voting in the Democratic primaries saying they would definitely vote Democratic in November - 20 points lower than the proportion of Republican primary voters saying they would definitely back the GOP nominee.
The danger confronting the Democrats is not the possibility of the defection of the Rev. Mr. Jackson's backers. Amid near-unanimous speculation that the Democrats would not in fact nominate Jackson for president, 65 percent of those who had voted for him March 8 said they would definitely vote Democratic in November, while another 17 percent would probably back the party nominee.
In contrast, only 45 percent of Southerners voting for Michael Dukakis on March 8, 36 percent of those backing Richard Gephardt, and 31 percent favoring Albert Gore said they were sure they would vote Democratic Nov. 8.
Whether or not the incumbent president is himself on the ballot, voters' assessments of his administration's performance are always an important factor in the next election. Does the electorate want to affirm Reaganism - or reverse it? Super Tuesday gave us part of the answer.
The substantial majorities that tell pollsters each election that they are looking for change say nothing about what kind of change they are seeking. In real-life politics the alternative to the status quo isn't the entire theoretical range of possibilities, but something quite specific - which generates its own opposition.
A question asked by the Roper Organization in December shows how difficult it is to read the electorate's verdict on Reaganism. ``Would you generally prefer a presidential candidate who will continue the policies of Ronald Reagan, or someone with more conservative policies, or someone with more liberal policies?'' Thirty-two percent wanted to continue Reaganism, and 36 percent to move toward more liberal policies, while 25 percent wanted a more conservative approach!
The fact is that many voters have contradictory or ambivalent feelings about Mr. Reagan. Getting them to sort all this out while answering a question on a public opinion poll is quite a trick. Still, many analysts believe that as the campaign proceeds, these assessments do get sorted out, with the November vote likely to be influenced significantly by the ultimate resolution.
George Bush's candidacy is bound to Reagan. Having served two terms as his vice-president, Mr. Bush probably couldn't have had it otherwise. But through his conduct - deemed ``loyal'' by friends and ``sycophantic'' by foes - Bush has made the inevitable an overwhelming necessity. In Campaign '88, Bush is Reagan.
Super Tuesday provided, then, the first major test of the current strength of the Reagan-Bush constituency - and Bush's 56 to 24 percent margin over Robert Dole was impressive. Major figures like him are not usually defeated by better than 2 to 1. Bush's performance suggests a strong desire of many Southern voters at least to affirm Reaganism rather than turn from it.
Everett Carll Ladd is executive director of the Roper Center for Public Opinion Research and professor of political science at the University of Connecticut.