Washington (CNN) – Congressional budget talks have entered a pivotal phase with some lawmakers working to lower expectations. But the two top negotiators and their staff have outlined how a possible deal, if they agree on one, could get through the House and Senate.

House Budget Committee Chairman Paul Ryan, R-Wisconsin, and Senate Budget Committee Chairman Patty Murray, D-Washington, are leading a conference committee convened to work out differences between House and Senate budget resolutions.

The marquee issue is more forced spending cuts, or sequester, set to take effect in mid-January.

The committee has until December 13 to agree on spending levels and how to tackle the sweeping cuts that would total $110 billion.

Democrats want to erase those cuts, while many Republicans want to spare the Pentagon, which is taking the biggest single hit.

The Ryan-Murray committee was tasked to come up with a deal as part of legislation passed in October that ended the government shutdown.

An aim is to return “regular order” to the congressional budget process whereby lawmakers approve spending bills and avoid future shutdowns.

While there is no agreement yet, two senior Democratic aides told CNN that staff is paving the way for one by determining how it would move through the Capitol.

But Rep. Chris Van Hollen, D-Maryland, one of the House Democrats on the conference committee, threw cold water on any imminent budget deal, telling CNN the budget talks “are going way too slowly.”

Van Hollen said progress so far was confined to “narrowing the scope” – instead of discussing how to replace the forced cuts scheduled to go into effect over 10 years, the two sides are discussing how to replace the sequester for the next two years.

Still, congressional aides told CNN that Republicans and Democrats would have to draft at least one spending bill, a prospect that would require more Senate votes than a normal budget package.

Why is that necessary?

Talks have gotten far enough to confront a political reality: any deal to roll back spending cuts must include an equal amount of new fees or revenues to make sure the deficit is unaffected. Otherwise, Republicans will not sign on. And any new fees or revenues require legislation. A non-binding budget report wouldn’t cut it.

Such a spending bill would likely require 60 votes to pass the Senate, but one senior Democratic aide told CNN they feel that if Ryan signed on, they’d be able to find the five Republicans needed to prevail there.

Budget sources indicate a few possible money-raisers are on the table, including: increased airline fees, changes in federal pension contributions and proceeds from auctioning electromagnetic spectrum.

Republican Rep. Tom Cole, R-Oklahoma, who also sits on the conference committee, described what he thought were four main goals of the group.

But taken together, they frame a modest plan – secure the savings from sequester, continue to lower the deficit, ease the sequester’s impact, and restore regular order in the congressional budget process.

“They’re not on the grand bargain scale, but let’s just hit some singles around here for a while. We don’t need to swing for the fences. Our batting average isn’t very good so let’s get on base,” Cole told reporters Monday.

The budget negotiators are working to agree on “top line” numbers for spending bills to cover the 2014 and 2015 fiscal years, and leave it to the Appropriations Committees to decide how to spread out the cuts to various programs, instead of using the blunt across the board formula set up by the sequester.

Those committees would have to put together an “omnibus” spending bill to fund the government before the January 15 deadline.

Cole said it’s possible that if the committees needed some time to finish the details of a deal over the December holiday period that Congress would pass some type of “very short-term” spending bill to avoid any government shutdown.

Asked about the possibility the House would stay in session longer this month to finish a deal, Cole said ‘the Speaker is pretty adamant that we are out of here on the 13th [of December].”

All sides stressed there are no agreements yet on spending levels or where to find any additional revenues.

But the fact that staff is laying out a possible legislative end-game signals something more than optimism. That concrete action is possible and could come as soon as this week.

A senior Democratic aide tells CNN that Murray will return to Washington on Tuesday, a week before the rest of the Senate, to continue direct talks with Ryan.