Wisconsin Democratic gubernatorial candidate Mary Burke attends the Rock County 4-H Fair on July 24 in Janesville, Wis. (Andy Manis/AP)

Democrats failed to dislodge Wisconsin Gov. Scott Walker (R) in a 2012 recall election. Former bicycle company executive Mary Burke (D) thinks she knows why.

"It became a one-issue race," Burke told Post Politics during an interview in Washington Wednesday, referencing the Democratic focus on Walker's law curbing collective bargaining for public employees.

The labor dispute was "not a winnable issue in Wisconsin," Burke added.

Democrats forced Walker into a recall election over his labor law. He defeated Milwaukee Mayor Tom Barrett (D) by an even wider margin than he did in 2010.

The recall, Burke said, "enabled Walker to build a national fundraising base." The governor is regarded as a potential 2016 presidential candidate.

Burke is the likely Democratic nominee against Walker this year. She wants to focus her campaign on jobs and the economy -- specifically on promises Walker has not fulfilled.  Polls show her in a close race against Walker.