WASHINGTON - Republican demands to end the ban on exporting crude oil emerged as a final negotiating point Monday as lawmakers scrambled to complete a year-end spending bill needed to keep the government running.

In return for lifting the four-decade-old ban, Democrats were seeking various environmental concessions, including extending tax credits for solar and wind energy production for five years, and reviving an environmental conservation fund. Democrats also were trying to block GOP efforts to roll back Obama administration environmental regulations, with Democratic lawmakers who traveled to the Paris climate talks returning energized to fight.

"It's like they all went to an international pep rally and got all this emotional wind at their back," GOP Rep. Kevin Cramer of North Dakota said in a phone interview.

Government funding runs out Wednesday at midnight, but Congress may need to pass another short-term extension of a day or two to complete work on the $1.14 trillion governmentwide spending bill. Negotiations have dragged on as the legislation has become an increasingly complex grab-bag for priorities and trade-offs large and small.

It's also intertwined with another massive bill extending dozens of tax credits benefiting interest groups across the political spectrum, sparking intense lobbying on numerous fronts.

The legislation was not likely to be finalized until Tuesday, which would probably mean final congressional passage toward the end of the week. Lawmakers would then head home for the holidays, having done their necessary work in typically messy and last-minute fashion.

"Many of us in the Senate and the House and our staffs worked through the weekend and have made a lot of progress," Minority Leader Harry Reid of Nevada said on the floor as the Senate gaveled back into session at midafternoon Monday. "We're not there yet."

The ban on exporting crude oil was instituted during energy shortages of the 1970s, but Republicans, and some Democrats, say it's long outlived any usefulness. They note a boom in domestic energy production. Environmental groups and most Democrats counter that the main beneficiaries would be big oil companies.

Cramer and Sen. John Hoeven (R., N.D.), whose state has experienced an oil boom, said they were hopeful the provision lifting the ban on crude would survive last-stage talks.

At the White House, press secretary Josh Earnest refused to weigh in on inclusion of the provision.