Republicans could lose their decadeslong hold on a Mississippi Senate seat if state Sen. Chris McDaniel emerges as their standard-bearer in the special election to replace former U.S. Sen. Thad Cochran, a fresh public opinion poll warns.

The Mason-Dixon survey showed McDaniel and Democratic former U.S. Agriculture Secretary Mike Espy neck and neck, with Espy leading McDaniel 42 percent to 40 percent, in a hypothetical matchup. That’s too close for comfort for Republicans in a solidly conservative Mississippi. In the same survey, Espy trailed Cindy Hyde-Smith, the other Republican running in the special election, 46 percent to 34 percent.