President Trump has landed on a familiar theme to try to rev up Republican enthusiasm heading into the final stretch of the 2018 campaign: Immigration. And specifically, Latin Americans crossing illegally into the U.S. via the U.S.-Mexico border. Immigration was in many ways the animating force of Trump's 2016 campaign, and while Republicans point to the Brett Kavanaugh Supreme Court confirmation battle as a boost to GOP energy, "the president realizes he needs to keep that momentum going," GOP strategist Matt Moore tells The Wall Street Journal.