Except for two things.
1 How does a priest know if someone voted for Obama unless the person tells him and
2 Even if he knows they did he may not know if they have been to Confession or what they Confessed.
All a priest can do about this is teach, preach and warn. If a Catholic wants to take Communion with grave sin on his soul the priest cannot stop them.
High profile politicians who support abortion are a different matter. The priest is reasonably assured that this individual is using religion and has not stopped supporting a grave evil.
Father Newman has clarified his statement. He wasn’t as hard line as he was described in the AP article:
http://catholicexchange.com/2008/11/15/114467/print/
Please read more carefully. I prefaced this with the word “knowingly”.