ATLANTA — Republicans see the 2014 midterm elections as a chance to capitalize on voter frustration with the problem-plagued health care overhaul, but the GOP first must settle a slate of Senate primaries where conservatives are arguing over the best way to oppose President Barack Obama's signature law. In intraparty skirmishes from Georgia to Nebraska, the GOP's most strident candidates and activists are insisting on a no-holds-barred approach. They accuse fellow Republicans — including several incumbent senators — of being too soft in their opposition to the Affordable Care Act and to the president in general.