Republican Dusty Johnson appears poised to win South Dakota's lone U.S. House seat.

Two weeks ahead of the South Dakota general election, Johnson has a 23-percentage point lead in the race, according to a poll commissioned by the Argus Leader and KELO TV.

In a survey of 500 registered voters likely to cast their ballots in the election, 54 percent said they would vote for Johnson if the race were held today. And 31 percent said they'd vote for Democrat Tim Bjorkman.

Two percent of those polled said they'd vote for independent candidate Ron Wieczorek and 1 percent said they'd support Libertarian George Hendrickson.

Another 12 percent said they were undecided.

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Jacksonville, Florida-based Mason-Dixon Polling & Strategy surveyed voters by telephone between October 18 and October 22. The margin of error is 4.5 percentage points.

From the get-go, Johnson has positioned himself as a spunky policy wonk with a moderate Republican platform. Bjorkman, meanwhile, played up his lack of a political history and his time working as a judge. He also centered his campaign around a promise not to accept contributions from political parties and PACs.

"I'm thrilled," Johnson said in a statement reacting to the poll. "Our optimistic, South Dakota first message is hitting home with South Dakotans. We have a lot of work yet to do, and I won't slow down."

Johnson, Bjorkman, Wieczorek and Hendrickson are vying for the state's lone U.S House seat vacated by U.S. Rep. Kristi Noem, who is running for governor against Billie Sutton and Kurt Evans.

Johnson breaks away from pack

Johnson carried higher approval numbers among those polled. Forty-four percent of those polled said they had a favorable opinion of the Republican. And 15 percent said they had an unfavorable opinion of him. Thirty-five percent had a neutral opinion about Johnson and the remaining 6 percent didn't recognize his name.

More:3 takeaways from the Argus Leader-KELO-TV U.S. House race poll

By contrast, 28 percent said they had a favorable opinion of Bjorkman and 10 percent said they had an unfavorable view of the Democrat. Another 39 percent said they were neutral on Bjorkman. Twenty-three percent of those polled didn't recognize Bjorkman's name.

Support for the candidates tended to break on party lines with 69 percent of Democrats saying they would support Bjorkman, 16 percent backing Johnson and 3 percent supporting Hendrickson or Wieczorek. Another 12 percent were undecided.

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Eighty-one percent of Republicans polled said they'd support Johnson, 7 percent said they'd vote for Bjorkman, 1 percent said they'd back a third-party candidate and 11 percent were undecided.

"No one wants to be down by a big margin in a poll 12 days out," Bjorkman said in a statement. "While these poll numbers show twice as big of gap as our internal polling has consistently shown, it does point to a key challenge: that while voters who know me have highly favorable views, almost two-thirds of the voters don’t know me well enough to have formed an opinion."

Independent and unaffiliated voters also favored Johnson, with 47 percent of those polled saying they'd back the Republican while 34 percent said they'd back his Democratic opponent. Seven percent of those polled said they'd support a third-party candidate and 12 percent had not yet made up their minds.

Across geographic areas, age groups and genders Johnson carried a lead over Bjorkman in the poll.

Follow Dana Ferguson on Twitter @bydanaferguson, call 605-370-2493 or email dferguson@argusleader.com