Congressional negotiators raced Saturday to write a compromise fiscal package that would limit the effect of tax increases due to take effect Jan. 1 while pushing many important decisions about the federal budget into the new year.

After a full day in which staffers sent papers back and forth, Senate Minority Leader Mitch McConnell of Kentucky left the Capitol shortly before 7 p.m. Saturday, telling reporters the two sides continue to try and reach a deal to avert the fiscal cliff.

“We’ve been trading paper all day and talks continue,” McConnell said. “We’ll let you know as soon as we have some news to make.”

But the talks clearly were in a new, urgent phase, with leadership staff expected to remain in the Capitol as long as necessary “to get where they need to be,” according to one person familiar with the negotiations.

“This is real,” not just for show, the source said.

GOP aides said they don’t expect to have more to say until after lawmakers are briefed Sunday afternoon.

The White House, meanwhile, remained in contact with negotiators and the president was kept informed of the status of the talks.