Harry Reid tells senators to stick around. (Reuters)

Senate Majority Leader Harry Reid (D-Nev.) told his fellow senators to stick around for the evening in case "fiscal cliff" negotiations lead to a breakthrough. 

"Everybody should hang loose," the senator said. "Something may break and we'll be able to get something done."

"I'm not overly optimistic, but I am cautiously optimistic that we can get something done," Reid said. 

Senate Minority Leader Mitch McConnell has appealed directly to Vice President Biden to try to break an impasse in negotiations for a last-ditch deal to avoid the “fiscal cliff” Sunday, as Reid stepped back from talks.

McConnell came to the Senate floor and announced he’d reached out directly to the White House for help shortly after Democratic aides said negotiations between McConnell (R-Ky.) and Reid (D-Nev.) had suffered a “major setback.”