The Republican presidential primary here is starting to look like a back-country sheriff's race.

It is mean and dirty, rife with innuendo, allegations of dirty tricks and political chicanery in the worst tradition of the politics of the Old South.

Old allies are calling one another names. And mud-slinging has become the only real issue in the race.

Ironically, the major protagonist in the affair is the campaign chief of George Bush, the former ambassador who tried to run as the "Mister Clean" of the Republican Party.

The chief antagonist is John B. Connally, the tall Texan who's been plagued by a wheeler-dealer image much of his political career.

And the chief beneficiary may be Ronald Reagan, who is watching his two chief rivals in the state sling mud at one another without any of it dirtying him.

Bush operatives have accused Conally of being sympathetic to gays and of engineering a plan to buy black votes for $70,000 -- allegations they have been unable to substantiate.

Bush claims to know nothing about the charges. "I was completely unaware of the allegations, and I haven't followed up on them," he told a news conference in nearby Florence today. "I'm concentrating on other things."

Connally, he added, in a rare personal comment about an opponent, "is running for king of South Carolina."

Bush's chief political operative in the state, Harry Dent, the former southern strategist in the Nixon White House, is at the center of the controversy. Dent and Bush state chairman Dick Greer authored a widely publicized memo last month that claimed Connally had endorsed gay rights "in, of all places, San Francisco."

And it was Dent who approved issuing a press release last week that said: "John Connally and his South Carolina campaign have made a deal with African Methodist Episcopal Church leaders for the delivery of 100,000 votes in the presidential primary.

"The deal is to provide the 100,000 black votes in return for $70,000 or more in 'walking around' money to get out the vote and then a quid pro quo to get an endowment for operating funds for Allen University (a black college) after the vote delivery."

But Bush forces, questioned about the affair, have been unable to substantiate their charges, and AME Bishop Frank M. Reid has drafted a statement calling on Bush to make a public Apology.

Connally, who was hinging his hopes for political survival on a good showing in Saturday's South Carolina primary, isn't letting the matter slide. "This is a typical scurrilous, unfounded allegation from dirty tricks Dent," he said in an interview Monday.

"He is the same man who was responsible for the secret slush funds of which Bush got $106,000 in 1970, $55,000 of which he didn't report as required under law."

Bush, a former congressman and CIA director, was an unsuccessful candidate for the U.S. Senate in Texas in 1970 and received $106,000 from a secret White House slush fund, called the "Townhouse Operation." Dent pleaded guilty to a minor charge in connection with his role in the fund. d

Sen. Strom Thurmond, who campaigns daily with Connally and was in the room where the alleged vote-buying deal was made, claims the charges are untrue.

"This is going to hurt Bush," said Thurmond who is revered in this state. "It doesn't pay to play phony, underhanded tricks."

The people who are enjoying it most are supporters of Ronald Reagan, the front-runner in the primary here. "This has hurt Harry Dent worse than anyone. But he isn't running," said Reagan's state coordinator, Lee Atwater. "The next person it hurt is John Connally. It brought up his old LBJ image.The next person it hurt worse was George Bush."

Bush aides are understandably concerned over the issue, which has been widely publicized here. State chairman Greer insists that the worst "gutter politics" have actually come from the Connally camp.

Last month, for example, he noted a letter and telegram from Connally to his executive state chairman, J. Anthony Campbell, that said: "The people of South Carolina know George Bush is being backed by the same Northeastern liberal establishment that tried to unseat Sen. Thurmond. His connection with the Rockefeller faction and the Trialateral Commission will not be accepted in South Carolina."

Greer acknowledge he couldn't substantiate the charges that Bush forces here have leveled against Connally. His only support for the charge that Connally endorsed gay rights -- an unpopular issue in this conservative state -- was a headline in the Houston Post that read "Connally Supports Gay Rights." But he said, "When one read the story, it was really kind of hard to tell exactly what he [Connally] said."

Payments for "walk-around money" to black groups are routine in South Carolina and much of the South. But the Bush campaign has been unable to come up with a witness to substantiate the charges it issued in a press release Feb. 28.

Jim Timmons, a paid Bush staff worker, issued the statement after receiving approval from Dent.