WASHINGTON (AP) - Sen. Lindsey Graham is threatening to hold up all nominations for federal government positions until survivors of last year's deadly attack on the diplomatic post in Libya appear before Congress. The South Carolina Republican made the threat Monday on his official Twitter account. The tweet said: "Where are the #Benghazi survivors? I'm going to block every appointment in the US Senate until they are made available to Congress. Graham is among lawmakers who are not satisfied with information they've received so far on the attack in Benghazi, Libya, that killed Ambassador Chris Stevens and three other Americans on Sept. Prominent nominations awaiting Senate confirmation include Janet Yellen for chair of the Federal Reserve and Jeh Johnson for secretary of the Department of Homeland Security.