The stakes of the stalemate are high -- and climbing.
The partial government shutdown entered its 14th day Monday, just three days before the U.S. government bumps up against its projected borrowing limit.
Talks both on ending the shutdown and on avoiding the debt ceiling have shifted to the Senate, as Senate Majority Leader Harry Reid and Minority Leader Mitch McConnell, along with other top senators, began discussions this weekend.
The Senate reconvened Sunday afternoon, with Reid saying he would do "everything I can throughout the day" to reach some sort of bargain with the chamber's Republican minority.
But a source familiar with the ongoing Senate discussions expressed doubt that any significant progress would be made Sunday evening. And the Senate adjourned shortly before 5 p.m. ET, showing no signs of such progress.
Still, Reid struck a positive note as he spoke on the Senate floor.
"I've had a productive conversation with the Republican leader this afternoon. Our discussions were substantive and we'll continue those discussions. I'm optimistic about the prospects for a positive conclusion," he said.
The Senate will meet again Monday at 2 p.m. ET.