President Obama talked about the economy Thursday at Northwestern University's Kellogg School of Management. (WhiteHouse.gov)

President Obama was at Northwestern University on Thursday to deliver an economic speech that, he and his team hoped, would lay out the case for why the public is better off today than they were six years ago -- even if they didn't feel it in their everday lives. Instead, Obama just gave every Republican ad-maker in the country more fodder for negative ads linking Democratic candidates to him.

Here are the four sentences that will draw all of the attention (they come more than two thirds of the way through the speech): "I am not on the ballot this fall.  Michelle’s pretty happy about that.  But make no mistake: these policies are on the ballot.  Every single one of them." Boil those four sentences down even further and here's what you are left with: "Make no mistake: these policies are on the ballot.  Every single one of them."

You can imagine Sen. Mark Pryor of Arkansas or Sen. Kay Hagan in North Carolina or Alison Lundergan Grimes in Kentucky grimacing when they heard those 28 words. That trio has spent much of the campaign insisting that this election is NOT about Barack Obama, that it is instead about a choice between themselves and their opponents.

Democratic Kentucky Senate candidate Alison Lundergan Grimes hits Sen. Mitch McConnell (R-Ky.) and distances herself from President Obama in an ad released less than two months before the general election. (YouTube/Alison for Kentucky)

The reason for this distancing strategy is obvious: President Obama is deeply unpopular in many of the states that will decide which party controls the majority in 2015. Of the seven seats rated "toss ups" by the non-partisan Cook Political Report, Obama lost four of them (Alaska, Arkansas, Louisiana and North Carolina) in 2012. He also lost in three Democratic-held open seats -- Montana, South Dakota and West Virginia -- now viewed as sure-thing pickups for Republicans. If Republicans only won Democratic-held seats where Obama lost in 2012, they would pick up 7 seats -- one more than they need to recapture the majority.

In many of these states, Obama's numbers are in a (much) worse place today than in November 2012. Just four in ten Louisiana voters approve of how President Obama is doing his job in a recent CNN/Opinion Research poll. In Arkansas, Obama's approval rating is at 31 percent, according to an NBC/Marist poll. Even in Colorado, a state Obama won in 2008 and 2012, his approval rating sat at just 39 percent in another NBC/Marist survey.

It doesn't take a political mastermind to realize that an ad in which the President of the United States says "Make no mistake: These policies are on the ballot. Every single one of them" might not be helpful to the Democratic candidates trying to run away from him this November.

So, why did Obama say it? My guess is that he wanted to make the stakes clear to a Democratic base that, by virtually every polling measure I've seen, is less enthusiastic to turn out and vote on Nov. 4 than Republicans.  The idea being that if you like Obama and his policies -- which his base, especially African Americans, still do -- then you need to show it by going out and voting.  The Obama political team is working under the assumption that if you dislike President Obama, nothing he says or does is going to change that reality. So, why not show the Democratic base that this election is worth fighting for?

I think that underestimates the impact of an unpopular president (on video no less!) bluntly insisting that an election in 33 days is indeed a referendum on his policies. Republicans couldn't have written a better script than that.