Early polls tend to lean liberal, since Republicans are getting ready to work or already at work, by that time.
Hugh Hewitt, said networks were throwing out exit polls, very messed up.
My experience in my younger days at a major political polling firm is that exit results at the House level are highly inaccurate. It's too hard to sample because the polling precincts must be chosen very carefully and they change so often that historical results to base the sample are largely worthless. At the Senate level, these exit polls can be very predictive.