Turnout, explained: the one slider that moves Mississippi's Senate race

Mississippi has some of the most racially polarized voting in the country, so turnout among different groups of voters can move statewide margins more than persuasion does. Our forecast page has a slider for this. Here's what it does and what it's based on.

The 2018 runoff is the best guide

The closest recent comparison to 2026 is the November 2018 special Senate runoff between Cindy Hyde-Smith and Mike Espy. It had the same incumbent, a midterm under a Republican president, and a well-known Democratic challenger. Hyde-Smith won by 7.3 points, much closer than most Mississippi federal races.

Turnout explains part of why. Statewide, the 2018 runoff drew 907,588 votes, 69% of the 1,311,354 cast in the 2020 Senate race. But turnout didn't drop evenly. In the whitest counties, runoff turnout was about 60% of the 2020 level; George County was the lowest at 53%. In heavily Black counties it was close to 80%; Humphreys County was the highest at 85%.

Across all 82 counties, the share of 2020 turnout that showed up for the runoff closely tracks each county's Black population share (correlation 0.80). In plain terms, Espy's runoff electorate was more Black than a typical presidential electorate.

How the slider works

The forecast starts from the 2018 runoff county map and shifts it evenly to our statewide projection, Hyde-Smith +11.7. We then estimate, from the county data, about how Black voters and other voters split in that runoff: roughly 98% Democratic among Black voters and roughly 14% among everyone else. This is an ecological estimate from county totals, not survey data, so treat it as approximate.

The slider changes Black voters' turnout relative to everyone else's, county by county. Here's what that does to the projected statewide margin:

For the Senate race, each 10% shift is worth about 4 points. Colom would need relative Black turnout about 31% above our baseline to tie, which is a very large surge. In a 2027 governor's race with a strong Democratic nominee, though, a 10 to 11% increase would be enough to make it a toss-up.

What the slider doesn't capture

The model doesn't move persuadable voters. That's what the national-environment slider is for. It also treats each county's population share as a stand-in for its share of eligible voters. And it can't account for a candidate-specific surge in one region, such as Colom's base around Columbus.

Absentee data can hint at turnout, but Mississippi doesn't report absentee ballots by race or party. As of Oct. 26, clerks had received 56,049 absentee ballots. That's more than double the 22,221 received at the same point in 2022, but less than half the 119,818 received in 2024.

Try the scenarios yourself, and see the methodology for every assumption.

Sources: Mississippi Secretary of State certified returns (2018 special runoff, 2020 Senate); U.S. Census Bureau ACS 2019–2023 5-year estimates, table B02001; MS SOS absentee report, Oct. 26, 2026; DeSoto County News for 2022 and 2024 comparisons.