Randall Terry never gets involved in anti-abortion activism and instead goes into mainstream politics.
Anti-abortion candidates have won elections before, but those who praise abortion clinic bombers and advocate capital punishment for abortion don't have a prayer. There simply aren't enough christian fundamentalists in the US, and I get the sense he's too radical for a good percentage of the fundamentalists too. OTL he can't win a *Republican* primary for state office, let alone having a shot at the presidency.
Even if you avert Roe v. Wade and the 1960s, it wouldn't work, because without legal abortion there's no reason for an anti-abortion movement to get off the ground in the first place. And single-issue candidates can't win the presidency anyway, and Terry would have a huge uphill climb to avoid that perception... especially since his views on *other* political issues are equally extreme.
Lyndon Larouche has a better chance.