AUSTIN, Texas - Politically crippled by the Vietnam War, President Lyndon B. Johnson still sounded like a candidate for re-election in private 1968 telephone conversations just before deciding to pull out of the race, according to recordings released Thursday.

Johnson, who had many of his White House conversations secretly recorded, sought support from labor leaders and talked of winning state primaries heading into that year's Democratic National Convention, despite potential threats to his candidacy by Sen. Robert F. Kennedy and others in his party.

Laced throughout the talks were Johnson's statements about the Vietnam War and the stinging criticism he faced from hawks and doves alike.

"It's a hell of a calculation to know what is enough and what is too much," Johnson said in one conversation, explaining the difficulties of deciding on troop levels.

The recordings, released by the LBJ Library and Museum, cover conversations Johnson had in early 1968, his last full year as president. They are among 600 hours worth of recordings released so far. Library archivists periodically release the tapes to the public in chronological order. Forty hours from 1968 are expected to be released in November.

The newly released recordings show Johnson worrying about the war, his efforts to combat domestic poverty, the value of the dollar and relations with Israel. In one conversation with former President Dwight Eisenhower, he assured Eisenhower he had no plans to use nuclear weapons in Vietnam.

"They show, I think, just this whirlwind of events - every day there's a new crisis," said Regina Greenwell, senior archivist at the LBJ Library.

On March 31, 1968, just 10 days before announcing he wouldn't run again, Johnson is heard asking the head of the United Auto Workers, Walter Reuther, to support his presidential campaign. He told Reuther he was going to defeat his opponents in the race for the Democratic nomination.

"These boys can't get this nomination. They're not going to get it. We're going to take these states, and they're not going to come close to it," Johnson said. "I've just got to have you stand up when the going gets tough."

In a conversation with Defense Secretary Robert McNamara, Johnson and McNamara discussed Army Gen. William Westmoreland's request for six more battalions in Vietnam that would have taken the troop level well beyond the planned 525,000 ceiling.

McNamara said it would be a mistake to call up reserves to fill the request.

Ultimately, after a study of the Vietnam options, Johnson's administration sent fewer troops than Westmoreland wanted.

In one discussion with Chicago Mayor Richard Daley, Johnson listens to Daley describe his conversation with Kennedy about his possible presidential candidacy. Johnson said he agreed with some of Kennedy's statements about the war and said he hoped for party unity.

He also blamed the New York Times for a leaked "scare story" about a possible escalation of troops in Vietnam, calling the newspaper "the root of all this trouble."

After Johnson's announcement that he wouldn't seek re-election, he talked by phone with Abigail McCarthy, wife of Democratic presidential candidate Eugene McCarthy, and with Republican Nelson Rockefeller. Both expressed shock over his decision.

"I hope you were shocked in a good way," Johnson told Rockefeller with a laugh. "You know, a fellow said, 'It hurts good.' "

Johnson went on to say he didn't have time to oversee the Vietnam War and peace effort while "chasing through primaries and trying to control conventions."

"Now I don't think any Republican or any Democrat can think I've got anything selfish to gain," Johnson said.

Johnson told Abigail McCarthy: "I've got nine months now to do nothing except, I won't spend one moment doing anything except trying to find peace."

Less than a week later, just after the April 4, 1968, assassination of the Rev. Martin Luther King Jr., Johnson listened to Atlanta Mayor Ivan Allen saying he was trying to maintain calm in his city.

Johnson's wife, Lady Bird Johnson, told Allen she was "troubled and sad."

"But God bless those who keep on striving and trying, and you're sure among them," she told Allen.

Mayor Daley of Chicago spoke with Johnson two days later about unrest in his city, and Johnson walked him through the legal steps of requesting help from federal troops.

"We're in trouble. We need some help," Daley said.

"Yeah, I was afraid of that," Johnson said. In seeing the rioting that was taking place, Johnson said, "I ate my fingernails off.