(NPN) -- Former Republican South Dakota governor Mike Rounds leads Democratic challenger Rick Weiland by nearly 13 points in the U.S. Senate race in the Nielson Brothers Polling/Northern Plains News poll conducted in late July.

While 42.9 percent answered they would vote for Mike Rounds, 30.2 percent said they would vote for Rick Weiland.

Independents Larry Pressler and Gordon Howie polled at 14.2 percent and 4.1 percent, respectively, with 8.6 percent “undecided.”

Nielson Brothers Polling polled South Dakota likely voters from July 23-28. The poll asked respondents to indicate on their phone dial pad their answer to the survey question: “If the election were held today would you vote for Republican Mike Rounds, Democrat Rick Weiland, Independent Gordon Howie or Independent Larry Pressler?”

With 578 respondents, the margin of error for this question is 4.04 percent.

Nielson Brothers Polling is an independent polling company in Sioux Falls, South Dakota. Northern Plains News is an online news and distribution service in Harrisburg, South Dakota.

The NBP/NPN poll also asked respondents about the favorability ratings of the U.S. Senate candidates.

Overall, Democrat Rick Weiland had a 35.4 percent “favorable” response, 28.7 “unfavorable,” and 22 percent responded that they did not know the name, with the remainder undecided. The margin of error on this question is 4.0 percent.

Republican Mike Rounds and Independent Larry Pressler both had higher favorables and unfavorables than Weiland. Rounds had a 44.3 percent “favorable” response, 40.1 percent “unfavorable” and 10.9 percent “undecided.” Only 4.7 percent had not heard of Rounds.

Independent candidate Larry Pressler had a 38.5 percent “favorable” response, 35.2 percent “unfavorable” and 16.4 percent “undecided.” Pressler’s “did not know” response was between Weiland’s and Rounds’ at 9.9 percent.

NBP did not measure Independent candidate Gordon Howie’s favorability ratings.

Probably the biggest question the poll answers is who is former Republican U.S. Senator Larry Pressler hurting the most—Rounds or Weiland.

According to NBP partner and pollster Paul Nielson’s reading of the cross tabulations, “Larry Pressler is taking significant support from both major parties with slightly more Democratic support.”

Pressler's support is almost split between Republicans at 40 percent and Democrats with 45 percent, with 14 percent coming from independents/others supporting him, Nielson said.

Nielson says 17.9 percent of Democratic respondents say they plan to vote for Pressler, along with 11.1 percent of Republicans and 18.9 percent of independents/others.

According to Nielson, 80 percent of Round's support is from Republicans, along with 12 percent Democratic and 8 percent from independents/others.

As to Weiland, Nielson says he derives 73 percent of his support from Democrats, 17 percent from Republicans and 9 percent from independents/others.

By party, 59.7 percent of Democrats had a “favorable” view of Weiland, 12 percent “unfavorable,” and 10.7 percent “undecided.” Fewer than 18 percent (17.6) of the Democrats polled said they had not heard of Weiland.

For Republicans, 18.2 percent had a “favorable” response to Weiland, 42 percent were “unfavorable” and 16.9 percent were “undecided.” Just over 22.9 percent of Republicans polled had not heard of Weiland.

For independents or those registered in other parties, 30.2 percent had a “favorable” view of Weiland, 24.9 percent “unfavorable” and 10.9 percent undecided. Nearly 34 percent did not know of Weiland.

Rounds had a 19 percent “favorable” response from Democrats, 65.1 percent “unfavorable” and 10.3 percent undecided. Only 5.6 percent of Democrats did not know who Rounds was.

Among Republicans, Rounds had 65.5 percent “favorable” response, 20.5 percent “unfavorable” and 11.4 percent “undecided.” Just over 2.6 percent not heard of Rounds.

For independents or those registered in other parties, 33.2 percent had a “favorable” view of Rounds, 44.1 percent “unfavorable” and 10.9 percent “undecided.” 11.8 percent did not know the former governor’s name.

For Pressler, Democrats gave him a favorability rating of 45.3 percent and an “unfavorable” response at 30 percent. with 16.8 percent of Democrats ”undecided.” A smaller percentage of Democrats had not heard of Pressler than Weiland at 7.9 percent.

As to his former party, Republicans were more unfavorably inclined than favorably inclined toward Pressler. Just over a third of Republicans (34.3 percent) polled at a “favorable” response, 40.4 percent were “unfavorable” and 15.5 percent were undecided. Fewer than 10 percent (9.8) had not heard of Pressler.

Among fellow independents and those from other parties, Pressler garnered a 32.6 percent “favorability” response, 31.2 percent “unfavorable,” and 19.1 percent undecided. Just over 17 percent (17.1) had not heard of Pressler.

The NBP/NPN poll also examined support on ideological belief rather than party registration, i.e., Tea Party, conservatives, moderates and liberals.

According to the poll, Weiland received 83.4 percent of the "liberals" vote, along with 39.8 percent of "moderates," 12.2 percent of "conservatives" and 2.8 percent of "Tea Party" supporters planning to vote for him.

Rounds pulls in the most "Tea Party" support at 67.5 percent and "conservative" support at 60.8 percent, with 25.9 percent of "moderates" and 3.9 percent of "liberals" saying they will vote for him.

Pressler received 19.7 of "moderates" support," 14.2 percent of "conservatives," 10.9 percent of "Tea Party" and 6.7 percent of the "liberals" support.

Howie had 14.1 percent of "Tea Party," 4.6 percent of "conservatives," 3.9 percent of "moderates" and no liberals saying they will vote or him.

The schedule for the release of additional polling results from Nielson Brothers Polling and Northern Plains News:

  • Tuesday: South Dakota governor’s race.
  • Wednesday: South Dakota U.S. House race.
  • Thursday: South Dakota Ballot Issues.
  • Friday: South Dakota politicians’ job performance.
  • Saturday: Direction of country and state, impact politicians taking positions on gay marriage and marijuana.
NPN graphic used with permission.