In the 03/04/08 Texas Democratic Primary, 10 pollsters competed. Forecasts ranged from a 3-point Obama win to a 6-point Clinton win. Clinton won by 3.4 percentage points.
ARG was the most accurate by 6 different measures of pollster performance. Zogby was 2nd most accurate. In this contest, the pollsters who polled through and including Monday night (Primary eve) produced estimates that were closer than pollsters who stopped polling sooner.
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