A prominent statistician has spoken: the Mississippi GOP primary run-off looks grim for incumbent Sen. Thad Cochran.

Nate Silver, the former New York Times statistician now with ESPN’s FiveThirtyEight, tweeted that, according to his site’s analysis, Cochran could well lose the Tuesday run-off against Tea Party challenger Chris McDaniel unless Cochran pulls in voters from the other side of the aisle.

FiveThirtyEight’s analysis of the race indicates McDaniel has a strong lead, and points to the heavily-Republican Rankin County as a pivotal spot in the race, where a strong performance by either candidate could swing the race.

U.S. Sen. Thad Cochran, R-Miss., speaks with the employees of Empire Truck Sales in Richland, Miss., Thursday, June 12, 2014, as he makes a campaign swing through mid-Mississippi. Cochran is involved in a tight runoff race for the GOP nomination for U.S. Senate, with state Sen. Chris McDaniel of Ellisville. (AP Photo/Rogelio V. Solis)

U.S. Sen. Thad Cochran, R-Miss., speaks with the employees of Empire Truck Sales in Richland, Miss., Thursday, June 12, 2014, as he makes a campaign swing through mid-Mississippi. Cochran is involved in a tight runoff race for the GOP nomination for U.S. Senate, with state Sen. Chris McDaniel of Ellisville. (AP Photo/Rogelio V. Solis)

RealClearPolitics’s polling average found McDaniel with a 6.3 percent advantage over Cochran Tuesday morning.

Cochran has been reaching out to black voters, who in Mississippi skew heavily Democrat, though questions have arisen about the extent of that outreach.

In Mississippi, any resident can vote in a party’s primary (a registered Democrat, for example, can vote in the Republican primary). But some observers have noted that it could be illegal for Democrats to vote in the Republican primary — or more precisely, Mississippi state law prohibits voters from participating in a party’s primary if they don’t intend to support that party’s candidates in the general election.

As Slate reported, legal decisions have rendered that rule effectively unenforceable.

Unless a voter marches up to a poll worker and declares their intention to participate in the GOP primary and then vote for the Democrat in the general election, it seems their participation can’t really be questioned.

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