[Men play cards in a tent at the transit center for refugees near northern Macedonian village of Tabanovce, while waiting for a permission to cross the border into Serbia, Wednesday, Feb. 24, 2016. Hundreds of refugees and migrants from Afghanistan and other nations remain stranded on borders of Macedonia with Serbia, unable to cross, and some of them forced backward toward Greece. (AP Photo/Boris Grdanoski)]BRUSSELS (AP) — The well-trodden path that has led hundreds of thousands of refugees and other migrants into the European Union's heartland is increasingly eating at the core of the once-tight bloc.