"I'm definitely at peace with myself," Sen. Paul S. Trible Jr. (R-Va.) said last night in a telephone interview after his startling televised declaration that he would not seek a second term. "This is a decision I've been wrestling with six or eight months."

For Trible, 40, a conservative Republican who has been in public life for more than a decade and was expected to seek reelection, the turning point came last month, after months of hearings before the joint Iran-contra committee he serves on, when he and his family vacationed on the Florida Keys.

"We had a wonderful time and it was then I made my final decision, finalized it with my family, and returned Labor Day weekend to implement it," Trible said.

He dismissed speculation that he decided to get out because of the possible entry of former Democratic governor Charles S. Robb. "I have never been in a stronger political position," he said.

"There was a problem -- which was that I didn't have enough time with my family," Trible said. "I just had two small children I loved and I want to see them grow up . . . . The Senate life just doesn't leave enough time for them."

Trible said that he conferred with former representative William Whitehurst (R-Va.) and a number of his Senate colleagues before reaching his decision.

"The response I've received has been an emotional one," he said. "Many opted for the Senate. They didn't see their kids grow up, and that weighs heavily on them."

Trible and his wife Rosemary have two children, Mary Katherine, 10, and Paul III, 6.

Throughout the interview, Trible stressed that he had not foreclosed the possibility of running for office again, including the governor's seat, which opens up in 1989. "I hope the future holds all kinds of opportunities," he said. "I very honestly have not thought beyond the next 15 months" when the term expires.

He said he does not know yet what he will do with the $1.5 million he raised in anticipation of another Senate run. He said he does not know yet whether those funds could be used in a bid for governor.

"I'm a young man and I hope I may have the opportunity to run for office in the future," he said, adding that he may also consider job opportunities in the private sector.

Trible said he decided to announce his decision now to give the Republican Party ample time to recruit a candidate, and said there is "no shortage of potential candidates," including Virginia's six-member House delegation, former state attorney general J. Marshall Coleman, and former Navy Secretary John Lehman.

"I think 1988 will be a great Republican year," he said, adding that his friend, Senate Minority Leader Robert J. Dole (R-Kan.), a presidential candidate, "will give a great boost to the GOP."