Republicans in Congress could immunize many electronic cigarette products from impending regulations by using a spending bill to shield not only e-cigs but vaporizers and hookahs from tougher federal oversight. It is the second year in a row the GOP is weighing such a move as a preemptory strike against the Food and Drug Administration, and it is stoking a debate over public health, small businesses and the lack of clinical data on the products’ health effects.