Tommy Thompson holds shrinking lead in Republican Senate poll in Wisconsin

— -- Former Wisconsin Gov. Tommy Thompson tops the crowded Republican candidate field in a new poll of next week's Wisconsin U.S. Senate primary. But results suggest Thompson's lead has narrowed.

Thompson,former U.S. Secretary of Health and Human Services and a 2008 candidate for president, received 28 percent support among likely GOP primary voters surveyed by Marquette Law School Aug. 2-5. Businessman Eric Hovde received 20 percent, former Rep. Mark Neumann received 18 percent and state Assembly Speaker Jeff Fitzgerald received 13 percent. An additional 21 percent remain undecided.

Those results suggest the race is trending more competitive as the Aug. 14 primary approaches.

"The GOP primary race continues to get closer," Marquette Law School Poll Director Charles Franklin said in his analysis. "Thompson held a lead of 20 percentage points over Hovde in June, 12 points in July and now 8 points in August. Likewise, Mark Neumann and Jeff Fitzgerald have rebounded from lower levels of support in early July."

In Marquette's poll conducted July 5-8, Thompson held 35 percent support, Hovde received 23 percent, Neumann received 10 percent and Fitzgerald received 6 percent. Twenty-five percent of respondents were undecided. That poll's margin of error was plus or minus 4.8 percentages points for likely Republicans.

In the August poll, Thompson leads a hypothetical general election matchup among likely voters against Democratic Rep. Tammy Baldwin 48 to 43 percent. Neumann ties Baldwin with 44 percent, Baldwin leads Hovde 44 to 41 percent, and Baldwin leads Fitzgerald 45 to 40 percent. Those four matchups are within the poll's margin of error.

The August poll's margin of error was plus or minus 4.4 percentage points for the Republican sample and plus or minus 2.9 percentage points for general election likely voters.