WASHINGTON — Congressional budget negotiators are near a deal in which Democrats would accept fresh revenue from user fees and Republicans would agree to more federal spending, steps that could avoid another government shutdown next year.

The two leaders of the 29-member bipartisan panel aiming to reach an agreement on budget savings to replace some automatic spending cuts set to start in January are hatching a minor deal in which both parties would have to compromise.

Instead of ending some corporate tax breaks, as Democrats prefer, revenue would come from raising user fees including for airline passengers. Republicans would have to accept higher spending levels than slated under current law, according to congressional aides.

Negotiations are continuing and “there are still issues to be resolved,” Senate Budget Committee Chairman Patty Murray, D-Wash., said Wednesday in Washington.

The two parties are “down to the last few items,” and are being “careful to say they don’t have a deal,” Rep. Tom Cole of Oklahoma, a member of the conference panel, said Tuesday. “It’s not the grand bargain but it’s a workable deal.”

With both parties eager to avoid another shutdown, the emerging deal gives them a framework to reach an agreement on government spending — either by the budget panel’s Dec. 13 deadline or before federal spending expires Jan. 15.

The budget accord would probably cap spending at about $1 trillion, instead of $967 billion, through automatic spending cuts known as sequestration and endorsed by House Republicans, Cole said. Democrats set a $1.058 trillion cap in their plan.

The fragile nature of the potential deal is demonstrated by some lawmakers from both parties who say they doubt it has enough support. To become law, the accord would have to be approved by the budget panel and then secure passage in both the Republican-led House and the Democratic-led Senate.

Maryland Rep. Chris Van Hollen, the top Democrat on the House Budget Committee and a member of the bipartisan budget panel, said there’s still no agreement even on the narrow list of issues. “It’s a jump ball right now,” he said, accusing Republicans of “taking things off the table.”

Meanwhile, some Republicans are pressing for a government funding bill that maintains current spending levels instead of a compromise that increases government expenditures that Republicans have fought to rein in.

“The only thing Republicans have, having voted for these debt-limit increases, is maintaining these spending cuts,” said Steve Bell, a former Senate budget adviser now with the Bipartisan Policy Center in Washington.

The debate probably will turn to a short-term spending bill in the range of $967 billion and $988 billion, Bell said.

The plan being negotiated by Murray and Rep. Paul Ryan, R-Wis., would avoid major changes to entitlement programs such as Social Security that Democrats are seeking to protect and tax increases that Republicans are ruling out.

Congress on Oct. 16 passed legislation funding the government through Jan. 15 as part of the agreement to end a partial shutdown, the first in 17 years.