A close VA-5 poll leaves our forecast where it was

One new poll of Virginia's 5th District has the race inside a few points. Expedition Strategies surveyed 602 likely voters from July 29 to August 1 and found the Republican at 47 percent and the Democrat at 44 percent. A three-point gap on that sample size is not a measurable lead, so the fair description is that the poll shows a close contest.

Our forecast moved very little. The model now gives the Democrat a 30 in 100 chance in VA-5, with a mean margin of R+5.3 and a 5th-to-95th percentile range running from R+22.5 to D+11.5. The previous run, produced this morning at 10:30 a.m. ET, had the Democrat at 29 percent and a mean margin of R+5.8. That is a shift of one percentage point in win probability and half a point in expected margin: the new number confirms the existing picture rather than changing it.

The gap between the poll and the model is worth naming plainly. Our estimate for the district sits several points to the Republican side of the Expedition Strategies result. A single survey of 602 voters does not resolve that on its own, and the width of our range — more than 30 points from the 5th to the 95th percentile — reflects how much is still unsettled 77 days out.

Nationally, our generic ballot average stands at D+6.7 across 26 polls fielded in the past 45 days. Our model gives Democrats a 93 percent chance of winning a House majority, with a mean of 242.4 seats against the 218 needed for control. One caveat on that figure is ours to own: our simulation correlates error nationally, by census division, by state and within each district, but we have no data to correlate demographically similar districts across state lines. Without that term, the House control probability is marginally firmer than it should be.