It's odd to say but the Wisconsin governor's race may be one of the sleeper contests in the country.

Odd to say because Wisconsin -- and its Gov. Scott Walker (R) -- spent the better part of two years in the national political spotlight after he pushed legislation that stripped public sector unions of collective bargaining rights and then faced down a recall effort in 2012.

Once Walker won the recall -- by a larger margin than he first got elected in 2010 -- most national observers moved on, assuming Walker would get re-elected in 2014 and might even run for president in 2016. But, while no one was watching Wisconsin has turned into one of the closest governor's races in the country -- with polling suggesting that Walker is in a dogfight with former Trek bicycle executive Mary Burke.

And this ad, which Burke is now running, shows that she has a potentially powerful message that goes to the number one concern of every voter: Jobs.

I've become convinced that the best (read: most effective) negative ads in the modern political world are those that feature a politician's own words. The video of Walker promising that he would create 250,000 jobs is political gold -- and something the Burke campaign can just keep running on TV  in lots of different iterations between now and November. And, while Walker may have answers for why he isn't going to meet that particular promise, it doesn't change the fact that he made a promise and looks unlikely to deliver on it. (If Walker somehow gets to 250,000 jobs by November, this attack has no legs and he almost certainly wins.)

The ad also makes clear that Burke understands that the way to beat Walker is on jobs and the economy not by focusing on his fights with public employee unions or the ethics investigation into some members of his team.  Both of those issues are ones that the Democratic base L-O-V-E-S. But, Burke gets that a) the Democratic base already hates Walker and is going to be behind her candidacy no matter what b) the recall election proved that bashing Walker on collective bargaining alone isn't a winner and c) the ethics stuff is far too convoluted to be effective in the context of a campaign with very few persuadable voters.

That's a very smart strategic decision -- and avoids repeating the mistakes of the recall. By running a different kind of race -- one focused wholly (or close to it) on jobs -- Burke plays both to her strengths as a businesswoman and to Walker's biggest vulnerability. Promises made but not kept are dangerous things in politics.

This is a very real race.