Texas is not enough for Nixon to win, and butterflies could also mean that Nixon is worse in the debate, not better. Or that he gets pneumonia in Alaska and is stuck in a bed until November, or that Eisenhower stays home instead of giving him luckwarm support as he did late in the campaign IOTL, or anything you want it to be, it's not an actual argument.
Anyhow, Gore was IOTL against the 1964 Civil Rights Act, the Southern Manifesto, in favor of the 1965 Civil Rights Act, while having liberal positions on Vietnam by the late 1960s.
So I'd guess that a lukewarm civil rights effort through the 1960s, a solid reelection in 1964 against Goldwater or someone else, possibly less involvement in Vietnam, and chances are pretty good that Humphrey might be his running mate in 1964.