( CNN ) Even in their greatest moments of triumph , American presidents can make decisions that in the long run will devastate their legacies . We have seen this in recent times , such as with President George W. Bush 's decision to invade Iraq . But the classic example was Lyndon Johnson 's experience with Vietnam . Fifty years ago , when the 89th Congress convened in January 1965 following Johnson 's landslide election victory against Sen. Barry Goldwater , LBJ was at the height of his political power . Liberal Democrats commanded huge majorities in both the House and Senate . The coalition of southern Democrats and Republicans had lost much of their power . Conservative Republicans were marginalized since nobody wanted to look anything like a protégé of Barry Goldwater . With the backing of a mass civil rights movement and organized labor , the White House was determined to push forward a huge domestic agenda ranging from Medicare to more anti-poverty programs to voting rights . Bills would soon be passing at a breathtaking pace as the nation saw Washington remake the social contract . But in these very same months , Johnson intensified America 's involvement in the war against communism in Vietnam -- a war that would prove to be disastrous , devastating and arguably the aspect of his presidency that continues to define him more than anything else . The previous year Johnson had already strengthened the nation 's commitment to the conflict in Southeast Asia . While President John F. Kennedy had increased the number of advisors working with the South Vietnamese in the fight against communist forces , Johnson set the groundwork for a much bigger intervention . He did n't do so with great confidence . In one of the most revealing White House recordings -- on May 27 , 1964 -- he and Georgia Sen. Richard Russell , a southern hawk who was Johnson 's mentor , have a lengthy conversation where both men express their doubts about whether this conflict was essential to the Cold War and whether it could ever be won . Russell said that it 's a `` damn worse mess that I ever saw . '' Russell added , `` I do n't see how we ever going to get out without fighting a major war ... . '' `` I just do n't know what to do , '' said Johnson . Regardless , because of the political pressure that Johnson felt from Republicans who were attacking him as weak on defense and since he agreed to the logic of the domino theory -- that if one country fell to communism others would follow -- Johnson requested that Congress authorize the use of force through the Gulf of Tonkin Resolution on August 4 , 1964 . Based on weak evidence about an attack on U.S. Navy destroyers ( Johnson admitted that the attack , if it occurred , was a mistake or the result of a decision by a low-level commander ) , Johnson worked with Arkansas Sen. William Fulbright to convince Democrats to support him with this resolution . The resolution was `` like Grandma 's nightshirt , '' Johnson said of the resolution , `` it covers everything . '' Fulbright assured his colleagues that they needed to pass the resolution to protect Johnson from Republican attack . If he intended to actually use his full power to deploy force in the conflict , Fulbright said , he would return to Congress for their approval . He never did . On February 15 , 1965 , LBJ received encouragement from a former president about how he was handling the situation . When Johnson told him he was `` having hell , '' including with the situation in Vietnam , President Truman assured him it was fine . Johnson thought he could learn from how Truman handled his problems with Korea . He reminded Truman that as a senator he had sent a letter in support of his efforts in Korea , even when Republicans like Ohio Republican Robert Taft were `` raising hell '' in the Senate . Johnson said he was `` doing the best I can '' , that when they `` go in and kill your boys you to hit back . '' Truman , who said he was handling the challenges well , gave him support , agreeing that you `` bust them in the nose every time you get a chance '' and `` they understand that language better than any other kind . '' But as the new year began other Democrats warned Johnson that he should not make use of this resolution for force . Two days after Johnson spoke with Truman , Vice President Hubert Humphrey implored the president in a lengthy and powerful memorandum to pull out . Humphrey argued that , for the first time , Johnson did n't have to fear Republicans attacking him as weak on defense . Liberals controlled Congress and he had just won a great landslide electoral victory . He could make a bold move and get out of this conflict before it was too late . `` Politically , '' Humphrey wrote , the Johnson administration is in a stronger position to do so than any Administration in this history . '' But Johnson did n't listen to Humphrey 's logic , and still feared the danger of being characterized as weak on defense just like Democrats had been in 1952 when they lost control of the White House and Congress . As Democrats in Congress spoke out against LBJ for Vietnam , he became more belligerent . He isolated Humphrey from his inner circle of advisors on foreign policy . He dismissed the criticism from Democrats and warned that they were giving propaganda support to the communists . We can hear this on a tape with one of Johnson 's greatest allies in the Senate , Minority Leader Everett Dirksen . On February 17 , 1965 , the two men discussed speeches that had been given by Idaho Sen. Frank Church and South Dakota Sen. George McGovern . Dirksen brought up how the two men had been `` teeing off '' against LBJ 's Vietnamese policy . Dirksen thought Johnson needed some defense from his `` friend on the other side of the aisle . '' Johnson told Dirksen that former President Dwight Eisenhower , a Republican , fully supported him . Johnson added that the kinds of speeches Church and McGovern were making posed the `` worst problem '' to the United States , more so than raids or ambushes or military accidents , since the speeches about the need for negotiation or withdrawal were used by the communists in pamphlets and newspapers . The statements undermined the confidence of the South Vietnamese government that the United States would continue to support them . At the same time that he spoke with such great bravado , he admitted to his advisors all of his fears and concerns . On February 26 , LBJ told Secretary of Defense Robert McNamara : `` I do n't think anything is going to be as bad as losing , and I do n't see any way of winning ... . '' On March 6 , many months after their haunting conversation about what could likely happen in Vietnam , Johnson did n't sound much better . When explaining that he was preparing to send Marines into the conflict , Johnson they were `` getting in worse '' and admitted that : `` The great trouble I 'm under , a man can fight if he can see daylight down the road somewhere . But there ai n't no daylight in Vietnam . '' In response Russell said , `` there 's no end to the road . '' During the very month that the House passed a sweeping version of Medicare and Medicaid and Congress prepared to send him an education bill to sign into law , Johnson got deeper into one of the most devastating military quagmires that the United States has ever faced . Johnson 's fears of being pummeled by the right , combined with his adherence to the `` domino theory '' about communism , would gradually drive him deeper and deeper into a disastrous war . Presidents are complex beings . Sometimes the very qualities that allow them to make great breakthroughs in public policy , that greatly improve the condition of the country , also allow them to implement decisions that become highly destructive . ​ .
50 years ago the stage was set for events that doomed Obama 's presidency . Julian Zelizer , LBJ was riding high after the landslide , could have avoided further controversy .