Pretending the past three years' dismal economy is someone else's fault is not likely to fool voters.

This month, during a speech in Osawatomie, Kan., and in an interview on "60 Minutes," President Barack Obama laid out the broad contours of his re-election strategy. Republicans would be wise to examine his words and prepare accordingly.

Mr. Obama will frame this election as a fight for the middle class. He told his Kansas audience that America was once a place where "hard work paid off, and responsibility was rewarded, and anyone could make it if they tried." Now, as he informed "60 Minutes" correspondent Steve Kroft, "the rules are rigged" against "middle-class families."

The president's tack is, in part, a reaction to his precarious standing among voters with high-school education or less. In a Gallup poll of Dec. 18, for example, his job approval with these voters—usually described as blue-collar workers—was 40%, down 26 points from January 2009. He can't win if his numbers in this group stay so low.

Mr. Obama will make "fairness" a major theme. He declared in Kansas that his goal was to "restore balance, restore fairness," and he then told Mr. Kroft that a "balanced approach" to the nation's deficit crisis required "everybody to do their fair share."

But resentment is not an effective political appeal. Americans tolerate unequal outcomes if they believe people have equal opportunity. Crude class warfare like Mr. Obama's has never been successful in presidential campaigns (consider candidates Mondale, Dukakis, Gore and Kerry). In fact, a Gallup poll of Nov. 28-Dec. 1 shows that fewer Americans (45%) now believe income inequality "represents a problem that needs to be fixed" than believed that in 1998 (52%).

Karl Rove is a former senior adviser and deputy chief of staff to President George W. Bush. He is a Fox News contributor and author of "Courage and Consequence" (Threshold Editions, 2010). To continue reading his column in The Wall Street Journal, click here