NASHVILLE — A new survey on Tennessee's Republican gubernatorial primary says the four-way Aug. 2 race remains close, with U.S. Rep. Diane Black leading Knoxville entrepreneur Randy Boyd by about a single percentage point.

Data Orbital's survey of 700 likely Republican voters found Black's support at 24.3 percent, while 23.1 percent of those surveyed said they supported Boyd.

Randy Boyd, left, and Diane Black are shown in this composite photo. (Source photos: The Associated Press)

Franklin businessman Bill Lee's backing was at 18.8 percent, while 10 percent favored state House Speaker Beth Harwell of Nashville.

Given the poll's 3.7 percent plus-or-minus margin of error and also another finding that almost one in five Republicans said they had yet to make up their minds, the contest was up in the air, according to the June 27-June 30 survey.

"Looking at the gubernatorial race in Tennessee, we see Lee with some growth from past polls," said Data Orbital President George Khalaf in a statement. "This growth can be seen in Lee's numbers in the younger age groups."

He said that "with the largest amount of undecided voters being the 36-50-year-old age group and on the middle of the political spectrum, this race will be key to watch as we approach the Aug. 2 primary."

The Arizona-based firm has polled in any number of political races in its home state. The polling website FiveThirtyEight has given the firm a B+ grade on its surveys. The Tennessee survey was based on a mix of interactive voice response using recorded prompts and live interviews.

During the polling period, Black's campaign began going on television with ad attacks on Boyd and Lee. Boyd's campaign responded and launched a counter-attack. Lee and Harwell continue to air positive ads touting their candidacies and no negative ads.

Data Orbital's poll contrasts with a recent survey of 1,040 likely Republican voters by Triton Polling & Research on behalf of the Tennessee Star, a conservative news website.

Triton's June 25-28 survey showed Boyd, a former state economic and community commissioner, leading Black by 5 percentage points, 32.6 percent to 27 percent. Lee had 20.3 percent support, while Harwell was at 6.9 percent.

Only 13 percent of poll respondents said they were undecided. The poll's margin of error was 3.1 percent.

The Data Orbital survey also asked likely GOP voters about their very or somewhat favorable views of candidates as well as very or somewhat unfavorable views.

Favorable views of Black were 63 percent, while unfavorable views were 25 percent.

Favorable views of Boyd were at 66 percent, while unfavorable views were 16 percent.

Favorable views of Lee were at 60 percent, while unfavorable views were 14 percent.

Favorable views of Harwell were at 51 percent, while unfavorable views were 21 percent.

The poll did not look at the Democratic field, where former Nashville Mayor Karl Dean and state House Minority Leader Craig Fitzhugh, D-Ripley, are vying for their party's nomination.

Early voting in state and federal primaries and county general election contests starts July 13.

Contact staff writer Andy Sher at asher@timesfreepress.com.