When President Obama announced plans to give a speech to the nation’s schoolchildren in September, it set off a frenzy among conservative commentators who deemed it, in the words of Florida Republican Party Chairman Jim Greer, an attempt to “indoctrinate America’s children to his socialist agenda.” Now, with the release of Katharine DeBrecht’s latest children’s book, “Help! Mom! Radicals are Ruining My Country!” — which lampoons senior Democratic members of Congress, including Speaker Nancy Pelosi of California and House Financial Services Chairman Barney Frank of Massachusetts — it is liberals’ turn to cry foul about the partisan poisoning of impressionable...