In Oedipus Rex, the Chorus acts as an intermediary, much like Jocasta will later when she comes between Oedipus and Creon. They try to be the voice of "reason" (logos) in response to the anger (pathos) of both Oedipus and Teiresias.
To us it seems that both the seer and thou,
O Oedipus, have spoken angry words.
This is no time to wrangle but consult
How best we may fulfill the oracle.
The Chorus seems to be saying that anger makes both men blind: it clouds the truth by placing emotion over logic.
The Chorus will end their song with several rhetorical questions:
But that a mortal seer knows more than I know—where
Hath this been proven? Or how without sign assured, can I blame
Him who saved our State when the winged songstress came,
Tested and tried in the light of us all, like gold assayed?
How can I now assent when a crime is on Oedipus laid?
They are acting as the voice of the audience here, not sure who to trust, the young, brash King Oedipus or the surly, experienced blind prophet Teiresias. Overall, their role is to portray the ideal audience, as they echo the play's themes throughout.