By Brendan O'Brien
MILWAUKEE (Reuters) - Wisconsin Governor Scott Walker, who is seeking re-election in November, has not seen any significant drop in his support since the release of documents on a probe into possible illegal campaign financing, a poll showed on Wednesday.
The first-term Republican governor received 46 percent support, while his likely Democratic challenger, Mary Burke, got 45 percent support, the Marquette Law School Poll taken from July 17 to 20 showed.
The results of the poll of 804 registered voters mirrored a poll taken by the same group in May, when both candidates received 46 percent support. Both polls had a 3.5 percentage- point margin of error.
In June, a U.S. appeals court unsealed hundreds of documents that showed state prosecutors accusing Walker and others of participating in a broad plan to circumvent the state's campaign finance laws during recall elections in 2011 and 2012.
Neither Walker, a potential Republican White House hopeful in 2016, nor anyone else has been charged in the investigation launched in August 2012 under a Wisconsin law that requires such probes to be conducted in secret.
Of the poll's respondents who heard of the investigation, 54 percent said it was "just more politics," while 42 percent said it was "really something serious."
Walker rose to national prominence among conservatives in 2011 when he pressed for legislation that restricted the power of many public-sector unions. His reputation grew the following year when he became the first U.S. governor to survive a recall election.
While Walker is seeking a second term as governor, he has made appearances in Iowa, New Hampshire and other states, and published a campaign-themed biography, adding to the perception he is preparing for a presidential run.
Burke, who has opposition in the August primary, is seen as the likely Democratic nominee for governor. A former executive at bicycle manufacturer Trek, Burke was state commerce secretary under Democratic Governor Jim Doyle from 2005 to 2007.
(Reporting by Brendan O'Brien; Editing by Jon Herskovitz and Peter Cooney)