In 1980, after performing poorly in the primaries, liberal Republican congressman John B. Anderson launched an independent campaign for president. He sparked some interest, getting around 20% in the polls (peaking at 24%, next to Carter's 35% and Reagan's 33%), before dropping to the mid-teens in August and finishing with only 6.6% of the vote.
With a PoD of no sooner than the start of his independent campaign, the challenge is to make John B. Anderson win the presidential election of 1980. Preferably, by winning an electoral majority and popular plurality, but if that is too implausible, he can also come up as a compromise candidate if the election goes to the House.
I can see two major PoDs: vice presidential selection and debates. ITTL, Anderson settled for former Wisconsin governor Patrick Lucey, a liberal Democrat with little name recognition, as his running mate, but others were considered, most notably Democratic New York Governor Hugh Carey and Republican Former Senator Edward Brooke (the first African-American senator since Reconstruction). Anderson also said (or at least implied) that he would have liked Democratic Arizona Representative Mo Udall as his running mate, but Udall was already committed to the Democratic ticket by the time Anderson's VP search began. Maybe a better running mate could have helped Anderson? Later in the election season, President Carter refused to debate with Anderson, fearing that he would spoil the election in favor of Reagan. This lead to only two presidential debates being held: one in September between Anderson and Reagan, which was won by Reagan, and one in October between Reagan and Carter. Having a better performance in more debates certainly would have helped Anderson.