Billy Carter told Senate investigators last week that Texas millionaire Clint Murchison tried to enlist his help last year in collecting money that Murchison said was owed to him by the Libyan government.

The president's brother said he couldn't recall how big a debt was supposedly involved but, according to informed sources, one of his sidekicks, Henry (Randy) Coleman, remembered it as "$200 million or something like that."

Both Carter and Coleman said they did nothing to follow through on Murchison's request, and a special Senate subcommittee that investigated Carter's Libyan connections is expected to conclude in an interim report today that there were no further contacts about the matter.

Senate investigators, however, may attempt to make further inquiries about Murchison's dealings with the Libyans and his approach to Billy Carter.

According to Carter, he and several friends of his from Georgia, including Coleman, were Murchison's guests at last year's Super Bowl game in Miami, where Murchison's Dallas Cowboys were playing the Pittsburgh Steelers.

Washington lobbyist I. Irving Davidson, who works for Murchison, has asserted that Billy and his friends were his guests, not Murchison's, and that he invited them only at the request of someone he knew at the White House.

The president's brother and Coleman gave a different account. Coleman, sources said, stated that Davidson called him and wanted Coleman and Billy to come to the Super Bowl as Murchison's guests.

According to sources, Billy said he might have met the millionaire at a party the night before the game, but they really didn't talk until the day after. The 1979 Super Bowl was Jan 21.

"I found out why we were invited," sources quoted Billy as saying in an interview. He said Murchison wanted to talk about getting payments on construction work he had done in Libya.

As the president's brother recalled it, the project involved an airfield built for the radical Arab regime.

"When I say airfield, I mean the complete thing, the barracks and everything else," Billy reportedly stated.

Coleman gave investigators a similar account, sources said. He reportedly recalled Murchison saying something about "concrete Army barracks."

"It seems to me like they owed him $200 million or something like that and he wanted us to help him collect it," Coleman reportedly said.

Davidson has said the only business he has done with Libya involved a ground-to-air communications system that one of Murchison's companies installed three years ago.

Neither Billy Carter nor Coleman could remember the millionaire's mentioning anything about a ground-to-air communications system, sources said.

In any case, Billy said he told Muchison he could not help get payments from the Libyans. Coleman said he told the president's brother he saw no reason to get involved in Murchison's problems, sources related.

Neither the president's brother nor Coleman could remember any further conversations with either Murchison or Davidson. Neither Billy nor Coleman ever got to the Super Bowl game either, though three friends from Georgia did. Coleman and Billy ended up watching the game on TV. Traveling with Billy can be, an exasperated Coleman reportedly told investigators, "aggravating as hell."

Davidson yesterday declined to comment on the matter, and Murchison could not be reached.