GOP has big lead in South Dakota early voting

More Republicans than Democrats are casting early ballots so far, a big advantage for U.S. Senate candidate Mike Rounds.

Overall around 20,000 Republicans have voted compared to 11,300 Democrats and 4,600 independents.

Republicans are outperforming even their built-in advantage in voter registration. Though 46 percent of South Dakota voters are Republicans, 56 percent of early voters are. Democrats make up 34 percent of the electorate, but just 31 percent of early voters.

About 6.3 percent of registered voters have already voted early, and most voters will cast their ballots on Election Day, Nov. 4. But early votes are valuable for candidates because they're in the bank -- a supporter who votes early gets their vote in even if they end up too busy to vote on Election Day, or if a late ad were to change their mind.

Usually more intense supporters are likely to vote early, and the winner of the early vote doesn't always win on Election Day.

Unlike some states, South Dakota's secretary of state doesn't publicly release the party registration of early voters. But it can be obtained by purchasing the voter file from the secretary of state. The partisan breakdown of early voting was provided to the Argus Leader by a political operative.

The data shows what party early voters are registered under. That doesn't guarantee they'll vote for their own party's nominee -- a recent Argus Leader/KELO-TV poll shows Rounds and Democrat Rick Weiland each with the support of about two-thirds of their party's voters.

More Republicans than Democrats have voted in all but seven counties -- including Moody County, where the sides are tied. The six counties where Democrats lead give them a 629-vote advantage. But there are three different counties where Republicans have early voting advantages bigger than 629 votes. They've got a 660-vote lead in Lawrence County, a 975-vote lead in Minnehaha County, and a whopping 2,342-vote lead in Pennington County.

There are more Republicans than Democrats in most counties, but Republicans are also turning out a bigger portion of their voters. In 55 counties a larger percent of Republican voters than Democratic voters have already cast their ballots, versus only 11 counties where Democrats are doing better.

The one Democratic triumph is Todd County, which has one of the higher turnout rates in the state, 245 more Democrats than Republicans voting early and a 1.6 percentage point advantage in the rate of party turnout. Even in heavily Democratic Shannon County, where Democrats have a 306-vote lead, the small population of Republicans are voting at a higher rate.

The Argus Leader weighted this partisan turnout by voting preferences in the recent Argus Leader/KELO-TV poll. For example, 66 percent of Democratic respondents told the poll they support Democrat Rick Weiland, so 66 percent of Democratic votes in each county were assigned to Weiland. Poll respondents who said they were undecided were ignored.

Under this projection, Rounds has 45.7 percent of votes, Weiland has 29.7 percent, and Pressler has 12.2 percent. Independent Gordon Howie has 2.5 percent.

Here's an interactive map of early voting by county, using public information that doesn't include partisan details: