New MD-1 poll matches our model's margin, and little else moves

A Z to A Research survey of 482 likely voters in Maryland's 1st District, fielded July 23-27 and posted on x.com, gives Republican incumbent Andy Harris 52 percent and Democrat Dan Schwartz 39 percent.

That is a 13-point margin, and it lands almost exactly on top of what our model already had. Our forecast now gives Harris a 91 percent chance and Schwartz a 9 in 100 chance, with a mean margin of R+12.9. The run three hours earlier had Schwartz at 10 percent and a mean margin of R+12.8. The new number confirmed the existing picture rather than changing it.

The uncertainty around that central estimate is still wide. Our 5th-to-95th percentile range runs from R+29.0 to D+3.4, so a Schwartz win is inside the distribution, at the far edge of it. One survey of fewer than 500 respondents does not narrow that range much.

Nationally, our average of 28 generic-ballot polls over the past 45 days stands at D+6.5. In the House, our model gives Democrats a 93 percent chance of reaching the 218 seats needed for a majority, against 6 percent for Republicans, with a mean of 240.1 Democratic seats. One caveat is ours to own: our simulation correlates error nationally, by census division, by state and by district, but it has no term linking demographically similar districts scattered across the map, because we have no cluster data for it. That makes the House control probability marginally firmer than it should be.

The Senate is closer. Our model gives Democrats a 49 percent chance of the 51 seats they need for control and Republicans a 50 percent chance of reaching 50, with the vice president a Republican and a 50-50 tie going to the Republicans. Our mean is 50.2 Democratic seats.