Is Obama's desire to subsidize manufacturing jobs related to the fact that is where the union jobs tend to be?

The NY Times notes:

In his State of the Union address, President Obama called for a wide-ranging package of policies to help create American manufacturing jobs, including trade enforcement measures, business tax breaks and worker training programs. In many ways, the proposal is surprising, as few economists now consider manufacturing a potent engine for job growth in the United States. . . .

Economists would advocate treating all businesses the same, but the Obama administration doesn't think so. So this begs the question about why should the president single out manufacturing for special benefits? My guess is that it is unions.