It may be much more parochial than abortion. If both candidates support abortion, other factors may come into play quite strongly:
The Catholic Church was strongly suppressed by the Russians, who killed tens of millions of Catholic Ukranians, siezed all their properties, and forced any parcticing Christian to adopt Russian Orthodoxy. To this day, the Russians have refused to return the churches to the Catholics. Since Yuschenko represents the Catholic-leaning West and independence from Russia, it makes sense Catholics would support him.
The position of Rome is that voters may support a pro-abortion candidate if there are "proportional issues." Several American bishops were quick to point out that in our Democracy, there were no issues proportional to abortion. In a country where neither candidate is pro-life, but where totalitarianism has resulted in a largely atheistic society which has slaughtered or starved tens of millions, there may well be proportional issues.
great analysis. thanks.