Ronald Reagan, having ambushed his own sourthern bandwagon in his anxiousness to link President Carter and the Ku Klux Klan, came under attack from all sides yesterday -- and finally issued a statement of retreat, regretting that his remarks had been "misinterpreted."

It was, according to Reagan's vice presidential running mate, George Bush, an apology. And, in an observation of this two-day-old presidential campaign, Bush also accused the Democrats of conducting a campaign of "groin-kicking."

Reagan contended, in his statement, that it was the Democrats who first raised the issue of the Klan, anyway.

At issue in this latest controversy surrounding Reagan was the Republican nominee's ad lib on Labor Day criticizing Carter for "opening his campaign down in the city that gave birth to and is the parent body of the Ku Klux Klan."

This prompted the president to counter yesterday that Reagan had committed "slurs and innuendo" against Tuscumbia, Ala., where Carter had opened his campaign Monday, and against the entire South. Carter, who desperately needs to hold his sourthern base intact if he is to win reelection, added: " . . . as an American and a southerner, I resent it."

Reagan's statement also prompted seven southern governors -- all Democrats -- to demand an apology, in a joint statement attacking "Mr. Reagan's callous and opportunistic slap at the South."

It prompted the local gongressman, Rep. Ronnie Flippo (D-Ala.), to inform Reagan by telegram that he had committed "an insult to Tuscumbia and the people who live there."

And it prompted Democratic National Chairman John White to call a press conference to say Reagan had slurred one region of the country "in a shoddy attempt to get an applause line" in another region.

But if applause was what Reagan was seeking, it was not what he received upon uttering his ad lib about the klan. The audience at the Michigan State Fair Monday night groaned audibly as Reagan tried to contrast his decision to campaign in unemployment-ridden Detroit with Carter's appearance in the city he said "gave birth to" the klan. (In fact, Tuscumbia has been the headquarters of one of the competing branches of the klan, but it was not the founding city of the klan.)

Carter, seeking to solidify his shaky sourthern political base, had opted to kick off his fall reelection effort with an appearance at a huge Labor Day rally in the South. When the klan showed up to picket, the president launched into a stinging attack on the KKK.

Reagan had been endorsed by the klan shortly after his nomination, and he quickly repudiated their endorsement.

Yesterday, Reagan campaign officials traveling with the GOP presidential nominee were clearly subdued, as they saw the impact from Reagan's one ad lib undoing much of the good they thought had come out of the otherwise carefully planned Labor Day kickoff. Several southern campaign chiefs telephoned senior campaign officials to express concern about Reagan's comment and the impact it could have on his chances of carrying several southern states.

"The governor had intended to say something that would draw a contrast between where he was campaigning and where Carter was campaigning," said one Reagan official. "And it just came out wrong."

Reagan officials have envisioned, based on their own polling, carrying at least two southern states -- Mississippi and Louisiana.

Yesterday, Reagan's Mississippi chairman, Rep. Trent Lott, said he did not believe that Reagan had seriously damaged his chances of carrying that state because of his klan comment. But Democratic chairman White said he believes that Reagan "now has no chance of carrying any state in the South . . . because he has slurred the entire region."

Reagan's statement yesterday was issued after several telephone conferences between officials traveling with Reagan and those here in Arlington headquarters.

"I am greatly disturbed about efforts to make the Ku Klux Klan an issue in this campaign," Reagan said at the outset of his written statement. "I also regret that certain remarks I made yesterday are being misinterpreted to mean something that was never intended."

As Reagan went on to tell it, someone in his audience wearing a Jimmy Carter mask had inspired him to make the adlibbed reference to the klan.

"A member of the audience who wore a Carter mask attracted my attention," Reagan said. "Jokingly, I said, 'I thought you were in Alabama.' I then added that Mr. Carter was speaking in the locale of the Ku Klux Klan headquarters, which statement had been included in a network newscast the evening before. I intended no inference that Mr. Carter was in my way sympathetic to the klan and in no way did I intend to disparage the city of Tuscumbia or the state of Alabama. Nor do I believe there is any place for the klan in the hearts of the people in the South. Since that time Mr. Carter and the members of his campaign staff have tried to exploit this situation for political purposes."

Reagan went on to say that the Carter people started it.

"The issue of the Ku Klux Klan was first injected into this election season several weeks ago by Mr. Carter's former appointee, Andrew Young, when he criticized me for attending the Neshoba County Fair in Philadelphia, Miss., and by Carter's Secretary of Health and Human Services, Mrs. Patricia Harris, who referred to the klan in an attack on my candidacy."

On Aug. 3, at the Neshoba County Fair, Reagan uttered familier code words of decades past. "I believe in states' rights," he told an overwhelmingly white audience.

Shortly afterward Young, who was Carter's first ambassador to the United Nations, wrote in a column that appeared in The Washington Post's editorial section about his own Philadelphia, Miss., journeys when three civil rights workers were murdered in that city in 1964, and said Reagan's choice of language reminded him of that era.

Harris, in a speech to the United Steelworkers convention on Aug. 6, noted that the klan had endorsed Reagan and that Reagan had repudiated the endorsement.

Earlier yesterday, Carter, responding to a question upon arrival in Kansas City for campaigning, called Reagan's initial comment "uncalled for, inaccurate, and I think it was something all southerners would resent."

Independent presidential candidate John Anderson said: "I'm disappointed the campaign will begin on that note. I think it was a very unfortunate comment. I dont't think it speaks well of Gov. Reagan."