A Jewish presence in Ancient Rome has been attested to from even before the Roman conquest of Judea. It was possible for prominent individuals to acquire Roman citizenship and at least under the Empire it was possible to acquire Senatorial rank through actions of the Emperor. Thus there appears to be a path by which a Jewish person could potentially enter the Senate.
However, there were some religious rituals associated with the Senate, for instance a sacrifice was made before each meeting, which may have made it incompatible (from an individual perspective) with Jewish observances (i.e. idolatry).
Were there any members of the Roman Senate who followed the Jewish faith?
Current Research: In addition to my general knowledge about Ancient Rome, I have read up a number of Wikipedia articles about the Roman Senate, and Jews in Ancient Rome, and I cannot find an answer to this question, nor can I find it by searching the web for related phrases.