WASHINGTON (AP) - Senate Republicans have blocked the confirmation of federal appeals court nominee Caitlin Halligan for the second time, denying President Barack Obama a key judicial appointment. Republicans say Halligan is too liberal to sit on U.S. Court of Appeals for the District of Columbia and cited citing her work on lawsuits against gun manufacturers. The National Rifle Association opposed her nomination. Democrats say the effort to block her is about maintaining a conservative majority on a key appellate court. A majority of senators, 51, supported her nomination, but Democrats needed 60 votes in the 100 member Senate to get it past Republican objections. Halligan serves as general counsel in the Manhattan district attorney's office and served as solicitor general for New York state. Obama first nominated her in September 2010.