The Deep South states, which in the last six presidential elections have caromed from candidate to candidate, from one party to another, appear ready for the first time in a generation to cast their electoral votes for the same man and the same party they supported four years ago.

What Greenville Mayor Bill Workman told the crowd here at a recent rally for President Reagan -- "It just feels good to be a Republican in South Carolina in 1984" -- could be repeated in almost any Dixie state, as the GOP looks forward to its biggest southern romp since Richard M. Nixon routed George McGovern in 1972.

This prospect looms in a year when Democrats have made their most massive and successful effort to expand their loyal black electorate in these states, and it suggests once again that the South may be on the verge of severing its historical allegiance to the Democratic Party.

Interviews with leaders of both parties and political observers in South Carolina and Mississippi cast doubt on any dramatic, overnight realignment. But the lure of Reagan's personality and policies, when combined with the growing impact within the Democratic Party of the ideas and followers of Jesse L. Jackson, make this a year of significant change and rising political tension within Dixie.

Whatever happens after Reagan's personal appeal is removed from the equation in 1986 and 1988, the Democratic Party -- and the politics of this region -- will never be the same.

In the last 20 years, the formula for Democratic victory in state and local elections throughout the South has been a solid black vote with whatever slice of the white vote is needed to produce a majority. But recent trends in the national and state parties have made it harder to keep that prescription working.

Ever since Strom Thurmond carried the banner of the Dixiecrat Party in the 1948 presidential election, southern Democrats have evolved toward consistent support of conservative presidential candidates, no matter what their party.

They rejected fellow southerner Lyndon B. Johnson for Barry Goldwater in 1964. The only Democrat to carry the South since 1964 was Georgian Jimmy Carter, and he lost to Reagan four years later.

"There has developed on the part of white people an assumption that anything that follows in the trend of Hubert H. Humphrey and McGovern and Walter F. Mondale is not worthy of consideration," South Carolina Democratic National Committeeman Don Fowler said. "The turnoff began with civil rights and the race issue. Then it got entwined with the antiwar, hippie image, and more recently with women's lib and gay rights . . . . It's reached a point where people here think it's us on one side and them the national Democratic Party on the other."

Southern Democrats have characteristically been the most conservative wing of the national party. But the increasing role of blacks inside the state Democratic parties is raising doubts about the continuation of that pattern.

Jackson has given voice to the belief of many black activists that the time has come for them to be more assertive, both on issues and on claiming offices.

"In terms of seizing the time and seizing the issues," said Leslie B. McLemore, a professor of political science at Jackson State University and Hinds County (Miss.) Democratic chairman, "the feeling is, it's now. We've waited long enough."

McLemore pointed out that the platform considered by the Mississippi Democratic Convention this year was "the most progressive" ever, including calls for a nuclear-weapons freeze and ratification of the Equal Rights Amendment.

Republicans say that the Democrats' leftward shift is sure to accelerate as the role and power of blacks increase.

"The Democratic Party is already very concerned that the white middle class is no longer voting in their primary in any numbers," South Carolina Republican National Committeeman John Courson said. "Especially with Rev. Jackson . . . activating his constituency, you may see even more of an exodus of moderate conservatives . . . . Inevitably, that means you will see more liberal candidates."

But the white moderates who have dominated the party are not yielding without a fight, and the battle for control is being contested more fiercely than ever.

South Carolina Democrats are still reeling from what party Chairman Bill Youngblood called the "nightmare" experience of a series of black-white confrontations in the Oct. 2 primary and Oct. 11 runoff for nominations in newly drawn single-member state Senate districts.

Although the controversial plan created 10 black-majority population districts in the 46-member Senate, only four black candidates came through the nomination struggle, with black activists blaming "bloc voting" by whites for the outcome.

Republicans are hoping that rumors of a black-voter boycott of the Nov. 6 general election prove true, and, in some cases at least, are doing what they can to promote the racial battle within the Democratic Party.

Mike McIntosh of Second Hand Rose auto rental agency in Columbia, S.C., told The State newspaper Tuesday that on the day before the Senate primary, Phil Antley arranged to guarantee payment on six rental cars used to carry voters to the polls in the primary.

What made the transaction unusual -- and a matter of controversy last week -- is that Antley is the Republican candidate in the race and that the cars were used by Edward Day, campaign manager for Mary Miles, a black political activist who was challenging the white incumbent, state Sen. Isadore Lourie, in the Democratic primary.

Miles failed in her race, and interviews with Republican officials in Mississippi and South Carolina produced a string of denials that the GOP is trying to accelerate a polarization policy of making the Democratic Party blacker and the GOP ever more "the white folks' party."

"The Republicans say they are not running a racial campaign but they are," said Jim Clyburne, a black who is director of the South Carolina Human Relations Commission. "People are against Walter Mondale because of his relationship with Jesse Jackson . . . . That's what the special-interest talk is all about."

"There's a perception that the Democratic Party is more interested in helping black folks than it is in helping white folks," conceded former Mississippi governor William F. Winter, a major architect of black-white Democratic coalitions.

Democrat Winter is the underdog in his challenge to Sen. Thad Cochran (R-Miss.), who could be the most successful southern Republican in courting black support.

Cochran's campaign manager, Jamie Becker, acknowledged that some Mississippi whites supporting Cochran may have become "fed up" with the increased black presence in the state's Democratic Party. But he said they also are "disenchanted with the direction of the national Democratic Party."

"They're basically defections toward a different philosophy of government and politics catalyzed by Ronald Reagan the person and by people like Thad Cochran the person," Becker said.

The process of polarization is helped by the fact that the Mondale-Ferraro ticket is a negligible presence in the Deep South, leaving the voters -- as Cochran said -- reacting to the conflicting appeals of the two most vivid personalities of the year, Reagan and Jackson.

Across the South, according to the most recent Washington Post-ABC News poll, Reagan is drawing upward of two-thirds of the white votes, and his reception at places like the University of Alabama fieldhouse testifies to the power of his personality and his advocacy of a strong defense and traditional religious values.

Mondale strategists say privately that the only southern prospects for the Democratic ticket are to eke out victories in Arkansas, Georgia and perhaps Alabama.

Meanwhile, Jackson's campaign to enroll black voters and bring them out to the delegate-selection caucuses and conventions last spring altered the balance of power inside the Democratic Party. Ed Cole, executive vice chairman of the Mississippi Democratic Party and a Jackson supporter, and other party officials told of what happened in Hinds County (Jackson).

The county Democratic executive committee used to be half black and half white. But this year, pro-Jackson blacks flooded the county convention and took 23 of the 30 executive committee spots, squeezing out many of the middle-class and trade-union whites who had provided resources for the party and kept it from becoming all-black. Later, five whites were added for better racial balance. But Cole said many longtime white allies still feel that "they don't have a home."

Overall, 31 of the 91 county Democratic chairmen and cochairmen in the state are black, as are 45 of the 100 members of the state party's executive committee. Many, including many well-educated, middle-class, more demanding young professionals, were drawn into the political process by Jackson.

Indicative of the changing of the guard in black political leadership was the election this year of Bennie Thompson, 36, a Hinds County supervisor and former mayor of Bolton, Miss., to replace veteran civil rights leader Aaron Henry as the state's Democratic national committeeman.

In South Carolina, where the growing independence or alienation of whites has decreased the turnout in Democratic primaries for a decade, many people noticed the darker complexion of this year's party meetings.

"At the Richland County Columbia Democratic Convention last spring, we must have had about 800 people," Fowler said. "I'd say about 500 of them were blacks. About 150 were feminists of one degree or another. The rest were mostly teachers or state employes. I was presiding and I couldn't see one white businessman or professional out there."

Such descriptions probably present a distorted picture of statewide or regional patterns. Mississippi and South Carolina are governed by moderate white Democratic governors who were elected with solid black support and a significant slice of the white vote.

"Our state government is predominantly Democratic and predominantly white," South Carolina Gov. Richard W. Riley (D) said in an interview. "I just don't buy the talk of racially polarized parties."

Jackson says neither does he. "That's an ungrounded fear," he said. "There's no room in the Republican Party for Democratic officials."

Ray Mabus, the Mississippi state auditor, said he was elected in 1983 with support among affluent whites and poor blacks, and sees himself as one of a new breed of white politicians unencumbered by the "baggage" of older white leaders who had to defer, at least in rhetoric, to southern traditions.

In state politics, the GOP beachheads are confined almost entirely to the major metropolitan areas. "In the rural areas," said Warren Tompkins, director of the South Carolina GOP, "it's still all Democrats. The encouraging thing is that we are getting more and more of the young people coming to our meetings even in the country, but changing habits and changing customs is a tough thing to do."

In Mississippi and South Carolina, about a half-dozen local officials and state legislators have switched parties this year. But some Republicans, including Cochran, see these conversions as exceptions to the general rule of Republicans building strength from the top down.

"It's just impossible to recruit a candidate in each of the counties and towns to run as a Republican," Cochran said. "It's a lot easier to recruit one person to run for governor or Congress."