the last book I ever read (The Passage of Power, excerpt three)

from Robert A. Caro's The Passage of Power: The Years of Lyndon Johnson:

When, in 1948, the place he had wanted so long--a seat in the United State Senate--finally opened up, Johnson had not leapt as the opportunity as his allies expected him to do, but instead had vacillated endlessly, until it was almost too late to enter the race, agonizing over the decision as to whether or not to run; his allies had finally threatened to run John Connally instead of him to nerve him up to announce his candidacy. And those men understood what was holding him back. Lyndon Johnson had long had the habit, in times of crisis, of telephoning Ed Clark, "the Secret Boss of Texas," at six o'clock in the morning to discuss the situation and ask for advice, and in 1948, in these calls, Ed Clark heard, over and over, one word. "Humiliation," Clark would recall. "That was what he kept repeating. 'I'll be humiliated. I'll be ruined. If I run, I'm going to lose--I'll be humiliated.'" Now, in 1958, a race for a much greater prize stretched before him--a race for a prize so vast that the attention not just of a state but of an entire country would be focused on it. So the possibility of defeat--of humiliation--loomed before him larger than ever, and "If he didn't try, he couldn't fail."

So he didn't try.