In a tight presidential race that both candidates say will turn on the economy, majorities of American voters believe neither has a plan to improve things. A new Fox News poll released Wednesday shows that by a 14 percentage-point margin, more voters think Barack Obama (41 percent) has a clear plan to improve the economy than think Mitt Romney does (27 percent). Still, a 53-percent majority says Obama doesn’t have a plan, and a 55-percent majority says Romney doesn’t. Romney has yet to seal the deal with all his party faithful, as less than half of Republicans (49...