Senate leaders on Wednesday worked out a deal to reopen the government and avoid a potential U.S. default as soon as midnight, sources told CNN's Dana Bash and Ted Barrett. Formal announcement of the agreement will come at 12 noon ET on the Senate floor, a Republican Senate aide told Bash. Republican leaders convened the Senate's full GOP caucus in the morning, and Sen. Kelly Ayotte of New Hampshire said on her way in that the announcement would be coming. "I understand that they've come to an agreement but I'm going to let the leader announce that," Ayotte said. Exact details of the Senate plan were not known. Nor was it clear how the Senate and House would proceed in considering the measure.