Chip and Caron Carter, whose marital problems and reports of an impending break-up thrust them into the national spotlight last summer, will be moving back to Washington, First Lady Rosalynn Carter indicated yesterday.

She said she expects her 27-year-old son, his wife, 26, and their 8-month-old son, James Earl IV, to move into the White House again sometime in January. They lived in a small apartment on the mansion's third floor for seven months until they returned to Plains, Ga., in late August.

They always thought they would live in Washington," the First Lady said, adding that her son's interest in politics is playing a part in the couple's decision to return. "Chip wouldn't want to miss the 1978 and 1980 (political) campaigns."

According to Rosalynn Carter, her son "only intended to stay in Plains during the peanut season" in an effort to help out in the family's peanut warehouse following the resignation of his uncle, Billy Carter, as managing partner.

"We didn't know what Kirbo was going to do," she said of Atlanta attorney Charles Kirbo, who is trustee for President Carter's blind trust which includes his 61 per cent share of the family peanut business.

Taking over management of the Plains firm about the same time that Billy Carter resigned was an Atlanta-based farm co-op which offered Chip Carter a job. Shortly after he started work, he slipped off a truckload of peanuts breaking his ankle. He continued to work but on crutches, according to the White House.

The warehouse job provided young Carter and his wife the chance to slip away from public view and presumably patch up their domestic differences. These flared into the open in mid-August following published reports that President Carter ordered Chip to move out after learning that he wanted to leave Caron. The White House press office, however, denied such reports.

Chip's return to Plains provided him another opportunity, Rosalynn Carter indicated yesterday. It permitted him to renew grass roots acquaintances for a future time when he intends to seek elective office, she said.

"Not yet," the First Lady said of any immediate efforts along those lines.

Chip resigned his $8,000-a-year part-time job with the Democratic National Committee on Aug. 1 but "he knows the door is wide open" to return, DNC executive director Paul Sullivan said yesterday.

"He's certainly welcome to come back. We miss him," said Sullivan who described Chip as a popular "name" or "sparkle" who was particularly effective as a fund-raiser for the party. He said he has had no recent contact with Chip about a job "but we did talk about it six weeks or so ago."

Meanwhile Rosalynn Carter said Chip and his family will make a brief weekend visit on Nov. 11 to see her and the President before they leave on their four-continent trip.

"I can't wait to see the baby," she said.