San Antonio mayor Julián Castro delivered a powerful keynote address at the Democratic National Convention. Unfortunately, a seductive speech and an honest accounting of the challenges facing this nation are two different things. Castro’s oration explored beauteous vistas of the Democrats’ imagination. The Chicago teachers’ strike has pushed that narrative smack dab up against uncomfortable reality.

Castro’s address was all about education. Recounting the struggles of his hard-working grandmother to build her children a better life, Castro launched into a paean to government education spending. Some things we can’t do alone, he said. Government investment in education is the key to tomorrow’s prosperity — the real pro-business approach. Then Castro excoriated Mitt Romney — and especially Paul Ryan — for proposing cuts to education funding.

Nowhere in Castro’s address was the problem of deficits addressed. The world was reduced to a battle between inexplicably cruel Republicans and caring, communitarian Democrats willing to “invest” (i.e. spend taxpayer dollars) in the name of the middle class.

Now comes Chicago. Among the best-paid educators in the country, the teachers union initially asked for a 30 percent raise over two years. Now they balk at a 16 percent in the middle of a bad economy, with Chicago’s budget deficit approaching $1 billion. So the choice Mayor Castro set up between heartless Republicans budget-cutters and Democrats willing to invest in education for the sake of the middle class is a false one.

#more#Faced with the reality of Chicago’s deficit and failing schools, even President Obama’s close associate, Rahm Emanuel, has been forced to push back against exorbitant salary demands and a union-backed school system that lacks accountability. Paul Ryan, the villain of Castro’s speech and the erstwhile opponent of Chicago’s mayor on so many national issues has said that, on the Chicago teachers strike, he and Romney “stand with Mayor Rahm Emanuel.”

Some say the teachers strike won’t mean much for the presidential campaign. After all, Emanuel is playing the budget-cutter and hard-nosed reformer here. If he wins, Obama might get some credit. That misses the point.

The Chicago teachers strike plays havoc with the Democrats fantasy convention narrative. Chicago’s looming deficit and failing schools have forced even Rahm Emanuel to do on the local level what the Democrats still refuse to do nationally. In Chicago, the Democrats’ comfortable dream of endless, cost-free government “investment” in schools and other projects has run up against reality.

Mitt Romney ought to make this point. His campaign should take the lessons of the Chicago teachers strike and use them to point out that the seductive narrative of the Democratic National Convention was in reality a dangerous illusion. Turn Charlotte’s appeal against itself by introducing it to the reality of Chicago.