New TX-28 poll shows Cuellar ahead by 11, and our forecast barely moves

A Public Policy Research/Texas Southern University survey of 600 likely voters in Texas's 28th District, fielded August 18-22, put Democratic incumbent Henry Cuellar at 45% and Republican Tano Tijerina at 34%. That is an 11-point margin, with about a fifth of respondents landing somewhere other than the two named candidates.

Our model gives Cuellar a 90 in 100 chance of winning the seat, with a mean margin of D+13.5 and a 5th-to-95th percentile range running from R+3.2 to D+30.1. The previous run, earlier on August 26, had him at 92% with a mean margin of D+14.5. The poll trimmed a point off the expected margin and two points off the win probability. Nothing in the new number changes the shape of the race as our model already saw it: Cuellar is the clear favorite, and the low end of our range still includes a narrow Republican win.

Nationally, our average of 27 generic-ballot polls over the past 45 days stands at D+6.5. Our model gives Democrats a 93% chance of winning a House majority, with a mean of 241 seats against the 218 needed. On the Senate side it gives Democrats a 45% chance of control; Democrats need 51 seats there and Republicans 50, because the vice president is a Republican and a 50-50 tie goes to Republicans.

One caveat on the House figure is ours, not the polling's. Our simulation correlates error nationally, by census division, by state and within each district, but it does not include a term linking demographically similar districts wherever they sit, because we have no cluster data for it. That makes the 93% marginally firmer than a fuller error model would leave it. We are not putting a number on the gap, because this run does not measure one.