Are politicians who are integral to passing pro-abortion laws automatically excommunicated from the Catholic Church? According to this article,

&quot;Any Catholic accomplice in the act of procuring an abortion, even
though not specifically mentioned in Canon #1398, receives the same
penalty of automatic excommunication. Here an accomplice is one who
assists in such a way that the heinous act would not have been
committed without his assistance.&quot;

If a politician votes for legislation that passes, say, that legalizes abortion in some capacity, is that politician therefore automatically excommunicated from the Catholic Church?
Excommunication is not exactly the same as recognizing grave matter.   Excommunications can't simply be overturned by going to confession.  A politician who votes for evil laws, like expanding people's rights to kill babies, may in some people's eyes be accomplices to abortion, but the particular sin they're culpable for before the congregation is scandal.

Scandal is an attitude or behavior which leads another to do evil. The person who gives scandal becomes his neighbor's tempter. He damages virtue and integrity; he may even draw his brother into spiritual death. Scandal is a grave offense if by deed or omission another is deliberately led into a grave offense.
CCC 2284

That Catechism passage had the word &quot;grave&quot; in it twice, which means it is very bad. It's the thing that Jesus said you'd be better off at the bottom of a lake than doing.

Therefore, they are guilty of scandal who establish laws or social structures leading to the decline of morals and the corruption of religious practice, or to &quot;social conditions that, intentionally or not, make Christian conduct and obedience to the Commandments difficult and practically impossible.&quot;
CCC 2286

So, not to let anyone off the hook, creating conditions where people want abortions is bad too.

However, to answer your question, it is not excommunication to be guilty of grave matter, but it is scandal upon scandal to allow people who are guilty of something like this to present themselves for communion.
And, for the record, at least one priest has denied Joe Biden, communion. The episcopacy just hasn't been using excommunication as a tool to tell people how to vote. I'd imagine they have reasons and I can only hope that they're being guided by the Holy Spirit.

In 2004, Cardinal Joseph Ratzinger, then head of the Church’s doctrinal office, wrote a memorandum to the U.S. Catholic bishops, explaining the application of canon 915 to the question of pro-choice politicians.


The case of a Catholic politician who is “consistently campaigning and voting for permissive abortion and euthanasia laws” would constitute “formal cooperation” in grave sin that is “manifest,” the letter explained.


In such cases, “his pastor should meet with him, instructing him about the Church’s teaching, informing him that he is not to present himself for Holy Communion until he brings to an end the objective situation of sin, and warning him that he will otherwise be denied the Eucharist,” Ratzinger wrote.


If the individual perseveres in grave sin and still presents himself for Holy Communion, “the minister of Holy Communion must refuse to distribute it.”


CNA News - Analysis: Will anything change on pro-choice politicians and holy communion?

But in the end, the US Bishops said each diocese is going to decide how to approach it.
Bishop Strickland in Texas would be on the side of the communion deniers but he might have it easy since the number of notable pro-choice Catholic politicians in the diocese of 55,000 people is pretty small.