story from washington. Those 11th hour talks to avoid the fiscal cliff. This evening here after they came to a halt, the vice president has been called in, now playing a central role. But time is... See More
story from washington. Those 11th hour talks to avoid the fiscal cliff. This evening here after they came to a halt, the vice president has been called in, now playing a central role. But time is running out. Just tonight and tomorrow left. And if no agreement, taxes will go up for all americans. In fact, the average american family would see a tax increase of more than $3,400. As congress convened, even the senate chaplain praying to avoid what the president called self-inflicted wounds. Let's bring in jon karl. He's been at his post every step of the way. The source has told you the vice president has been called in on this. Reporter: That's right. I'm told the vice president is now playing a direct role in these negotiations, trying to get to a deal, a last-minute deal, a key player in the final hours. President obama set off the high-stakes weekend scramble friday night, imploring congressional leaders to take action immediately. The american people are not going to have any patience for a politically self-inflicted wound to our economy. Reporter: With that harry REID AND mitch McConnell launched a last-ditch effort to craft a bipartisan plan to protect most people from a tax hike going into effect on new year's day. They negotiated all day saturday. Saturday night there was an offer. By this morning, a clear sense of optimism and warnings that failure would be unthinkable. There are certainly no breakthroughs yet, but there's a possibility of a deal. If we are not able to reach an agreement, it will be dire. The morning's optimism turned into the afternoon's pessimism. The senate opened for business at 1:00 p.M. With the ominous prayer from the chaplain. Look with favor on our nation and save us from self-inflicted wounds. Reporter: Soon democratic leader reed acknowledged he had not been able to make a counteroffer to republicans. It's just that we're apart on some pretty big issues. Frustrated with theasse, republican McConnell said he called vice president biden, urging him to get involved. I'm concerned about the lack urgency here. I want everyone to know I'm willing to get this done, but i need a dance partner. Reporter: After a roller coaster of a weekend, the bottom line is, there is still no deal. Although the white house says the president remains modestly optimistic and harry reid said they would work through the night. But of course time is almost out. And millions are americans are watching. Jon karl at the white house tonight, jon, thank you.
This transcript has been automatically generated and may not be 100% accurate.