House Speaker Paul Ryan, R-Wisconsin, appeared skeptical Monday that Congress would wrap up its agenda this week.
"I've got two big issues remaining: expiring provisions in the tax code and obviously funding the government, and that's what we're working on this week," Ryan told a radio station that serves his hometown of Janesville, Wisconsin.
"That's what we're working on this week, and it might take us more than just a week to get these issues put together correctly," he added.
Congress must pass a $1.1 trillion spending bill by the end of Friday to fund the government through next September and avert a government shutdown. Lawmakers are also trying to reach a deal on renewing expired tax breaks.
On Monday morning, congressional aides told CBS News that issues over the spending package have not yet been resolved.
"Negotiations continue. An agreement is expected this week," a spokeswoman for Republicans on the House Appropriations Committee said.
A Democratic aide said Republicans and Democrats "traded proposals all weekend" and that negotiations are ongoing.
Last week, House Majority Leader Kevin McCarthy, R-California, predicted that the government would not shut down, but Republicans and Democrats remained at odds over the policy riders that would be attached to the spending bill.
Democrats rejected the GOP's initial proposal because Democrats said it contained more than 30 "poison pill" policy provisions that included "numerous anti-environment, anti-worker, anti-Dodd-Frank riders as well as the House Syria refugee legislation."
It's unclear whether the final package will include a provision to pause the Obama administration's Syrian refugee plan, which the House passed through a standalone bill last month. The White House and most Democrats are opposed to suspending the plan to take in at least 10,000 more refugees from Syria over the next year.
CBS Radio's Steven Portnoy contributed to this story.