(By the Assosiated Press)--Tapes of two 1964 telephone conversations released today by the Presidential library here showed that almost a year before President Lyndon B. Johnson began the large-scale buildup in Vietnam, he called the war ''the biggest damn mess I ever saw'' and lamented, ''I don't think it's worth fighting for, and I don't think we can get out.''
Johnson made the complaint in a May 27, 1964, telephone conversation with his national security adviser, McGeorge Bundy, and another one the same day with his close friend and political mentor, Senator Richard B. Russell, Democrat of Georgia.
They show that six months after he became President, Johnson agonized over what to do about Vietnam and was tormented by the prospect of sacrificing American soldiers to a war he considered pointless.
Although he believed public opinion was already against the war, Johnson also worried that Congress might run him out of office if he tried to withdraw.
''They'd impeach a President, though, that would run out, wouldn't they?'' he asked.
He also spoke movingly of not wanting to endanger United States soldiers in Vietnam.
''I've got a little old sergeant that works for me over there at the house, and he's got six children, and I just put him up as the United States Army and Air Force and Navy every time I think about making this decision,'' he told Senator Russell.
''Thinking about sending that father of those six kids in there and what the hell we're going to get out of his doing it? It just makes the chills run up my back.''
Senator Russell, the chairman of the Armed Services Committee, replied: ''It does me, too. We're in the quicksands up to our neck, and I just don't know what the hell to do about it.''