Yes. But politicians are a little different. Pro-abortion "Catholic" politicians are "obstinately persist(ing) in manifest grave sin" within the meaning of Canon 915. The important difference is that Canon 915 does not concern itself with subjective culpability.
Those who persist in manifest grave sinIt can be more difficult to determine whether in a particular case all four elements referred to are simultaneously present:http://en.wikipedia.org/wiki/Canon_915
which is grave,
which is manifest,
and which is obstinately persevered in.
The action must be a sin in the eyes of the Church, not merely something distasteful or irritating; personal guilt on the part of the person concerned is not required.
The sinful action must be "seriously disruptive of ecclesiastical or moral order".
To be manifest, the sin must be known to a large part of the community, a condition more easily met in a rural village than in an anonymous urban parish. Knowledge by the priest alone, in particular through the sacrament of confession, is not a justifying cause for denying Holy Communion. Public withholding of the Eucharist for little-known sins, even grave sins, is not permitted under canon law.
Warning to desist, in the light of canon 916, from the sin before coming to receive Holy Communion is usually, but not necessarily, required to determine the existence of obstinacy.