Biden is required by church law to follow the moral rules of the Church. He cannot support abortion in any capacity, including the political. It is his moral duty to protect innocent life and to persuade others to do so. There is no branch of Christianity which teaches that there is a right to an abortion. The free exercise and establishment clauses do not apply to pro-abortionism. Protestants (or liberal Catholics) who claim there is a religious basis for supporting abortion rights are in error.
The Church does not teach that it is a religious mystery that unborn children are human beings worthy of lawful protection from harm, but as a fact. Biden , therefore, would not be "imposing" an article of faith if he were to support pro-life positions. It doesn't require a leap of faith to acknowledge unborn children as human beings worthy of respect and protection from harm.
Correction: He cannot support direct abortion in any capacity
142. Ethical delegitimization applies to all forms of direct abortion, since it is an intrinsically blameworthy act. The use of substances or means which impede the implantation of the fertilized embryo or which cause its premature detachment is also an act of abortion. A doctor who would knowingly prescribe or apply such substances or means would cooperate in the abortion.
If the abortion follows as a foreseen but nor intended or willed but merely tolerated consequence of a therapeutic act essential for the mother's health, this is morally legitimate. The abortion in this case is the indirect result of an act which is not in itself abortive.273