Model cuts Democrat's Louisiana Senate chance to 2 in 100 overnight

Our forecast of the Louisiana Senate race moved toward the Republican between runs a day apart. On August 16 at 10:15 PM ET, our model gave Democrat Jamie Davis a 10 percent chance. As of August 17 at 4:01 PM ET, it gives him a 2 in 100 chance, with Republican Julia Letlow at 98 percent. That is a drop of 8.2 points of Democratic win probability in one day.

The center of the estimate barely moved. Our model's mean margin was R+15.1 at the earlier run and is R+14.2 now, a shift of about a point toward the Democrat. What changed is the width around it. The earlier run put the 5th-to-95th-percentile range at R+34.9 to D+4.4, leaving some simulated outcomes on the Democratic side of the line. The current range runs from R+25.5 to R+3.0, with no Democratic outcomes inside it.

No new Louisiana polling arrived between the two runs. The only survey of this race in the payload is a Public Policy Polling poll of 518 registered voters fielded July 21-22, which had Letlow at 41 percent and Davis at 37 percent — close, and taken well before the earlier run. So the movement is our model's, and the cause is not something the payload identifies. We are not going to assign one.

The seat is open; Republican Bill Cassidy is the sitting senator and is not among the candidates in this forecast. Nationally, our model gives Democrats a 45 percent chance of winning Senate control and Republicans 55 percent, with a mean of 50.0 Democratic seats. Democrats need 51 seats for control and Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to them. Our generic-ballot average stands at D+6.7 across 26 polls over the past 45 days.