Why Congress keeps letting deadlines pile up and pushing them back

When asked Monday about whether his sweeping social spending and climate agenda -- the Build Back Better Act -- can pass the Senate before Christmas as he and congressional leaders want, President Joe Biden responded, "As early as we can get it. We want to get it done no matter how long it takes."

And that answer suggests it could be yet another deadline missed.

In the face of numerous reports that the deadline is slipping to January, and comments to that effect from some key Democrats with objections, Senate Majority Leader Chuck Schumer told his his caucus in a letter Monday that the goal is still to pass the legislation "before Christmas and get it to the president’s desk."

But even if Build Back Better passes the Senate before lawmakers are taking down Christmas decorations, they are still facing several dates circled in red before the end of 2021, some of which lawmakers have set for themselves and may still be on track to miss.

The most pressing is raising the debt limit in the next few weeks before financial disaster strikes.

Treasury Secretary Janet Yellen has previously painted a grim picture if the U.S. were to default on its debt, warning Congress back in September of "calamity" from a "manufactured crisis" as Senate Republicans blocked Democratic efforts to raise the ceiling.

Despite the warnings, lawmakers eventually came to only a short-term solution in October, raising the debt limit by $480 billion until Dec. 3, to return to the issue when it became impossible to put off any longer.

Why does this keep happening and at what cost?

"The contemporary Congress really is fueled by deadlines, and sometimes they're fueled by deadlines and it's helpful to them, and sometimes they're fueled by deadlines and it's not helpful to them," Brookings Institution senior fellow Molly Reynolds told ABC News.

Most years in December, with the holiday season in full swing, everything comes down to the wire on Capitol Hill. But Reynolds said that while legislators face a mountain of work to finish each year, 2021 stands out.

In addition to the debt ceiling and Biden's agenda, measures perennially seen as must-pass, such as the National Defense Authorization Act and critical funding bills, still hang in the balance.

Reynolds said Congress sometimes appears to procrastinate, working right until deadlines or missing them altogether, because it needs more time to work things out.

"Kind of like a college student getting an extension on a paper," she said.

But in other cases, lawmakers working to the last minute before a deadline is the failure to find common ground on disagreements, and Reynolds said partisanship and dissent has been everywhere this year, especially among House and Senate Democrats.

In setting soft deadlines, such as when leadership wants to see progress on Build Back Better, the strategy can be to break a logjam and force action.

"In most cases, as we've seen them, obviously the bill itself has not been finished, but there's been kind of incremental progress," Reynolds said.

Biden has previously played down months of Democratic infighting that delayed progress on infrastructure and reconciliation negotiations this fall.

"Right now, things in Washington, as you all know, are awfully noisy. Turn on the news and every conversation is a confrontation, every disagreement is a crisis," Biden said in October about a plan proposed in framework form months before.

Jim Manley, a Democratic operative and a spokesperson for former Senate Majority Leader Harry Reid, said legislators setting time limits for themselves is just the way Capitol Hill functions in its present state.

"What has become very clear is that Congress is unable to get anything done without facing a deadline," Manley said.

"It's now become a frequent occurrence and is a significant part of the leadership -- whether Republican or Democrat -- playbook when they're running the place," he added.

Washington University professor Steven Smith sees constant short-term deadline-setting, particularly when it comes to the appropriations process and stopgap government spending bills, as a "function of political failure."

"How can it become worse? The Senate failed to pass any of the 12 appropriations bills -- not one. They didn't even vote on them on the Senate floor, let alone pass them. How could it be worse than that? This is as bad as it gets," Smith said.

Smith added he believes deadlines allow lawmakers to force themselves to revisit and address a variety of issues and policies.

It’s not healthy for government programs to be consistently running on stopgap funding, because short-term funding naturally creates challenges when agencies are trying to plan ahead, Reynolds said.

She also said more political conflicts have found their way into the appropriations process -- the start of the fiscal year each October is often preceded by missed deadlines and, some years, government shutdowns.