If most politicians who want Americans to become engineers are lawyers then it's because most politicians are lawyers (or something similar). Selection bias. This explanation is simple and non-malicious.
But maybe the preponderance of lawyers in American politics is part of the problem. Engineering or science is a far more common background among national leaders in Europe and Asia - and this may turn out to provide a massive competitive advantage over the US in the future. Thomas Friedman in "the world is flat" mentions this possibility a few times.
I voted for Barak, and I'm happy to have him as my president. But actions speak a lot louder than words. If this immensely popular president is a lawyer who encourages kids to be engineers, the kids will who admire him will want to become lawyers who encourage people to be engineers.
