(Darla Cameron / The Washington Post)

This post has been updated.

When we last left you in this series, congressional budget experts told The Fix that the government looked more likely than not to shut down over partisan bickering at midnight Oct. 1.

Now we're pretty sure a shutdown has been avoided; though it's not a guarantee.

Former speaker John A. Boehner (R-Ohio) drastically changed out shutdown prediction this fall when he suddenly announced his resignation, taking the wind out of the sails of conservatives who threatened to oust him if he didn't agree with their demands.

On his way out the door, Boehner worked mostly with congressional Democrats and the White House to pass a two-year budget deal that also raised the debt ceiling into 2017. Then Congress elected a new speaker, Rep. Paul D. Ryan (R-Wis.), and gave itself a year-end deadline to pass a spending bill to put dollars to that budget.

Attempting to pass that spending bill is Congress's latest challenge. On Tuesday, Republican and Democratic leaders announced they had a deal. But until it passes both chambers of Congress and is signed by President Obama, we're on shutdown watch.

With the deadline for another government shutdown fast approaching, here the eight terms you need to know in order to understand what Congress is debating. (Sarah Parnass/The Washington Post)

That's because the political dynamics that led experts to predict a shutdown this fall haven't substantially changed. Ryan faces the same pressures from conservative lawmakers and Democrats as Boehner did. Lawmakers on both sides of the aisle would love to use the spending bill to send political messages, including: no funding of the agency that handles refugees until the Obama administration can confirm that its process for vetting Syrian refugees is safe; limit the Environmental Protection Agency's efforts to control greenhouse gas emissions; and lift the ban on U.S. oil exports.

[Paul Ryan's first real test as speaker is (surprise!) a no-win scenario]

All of that said, this time around, our congressional budget experts think the dynamics are just different enough that these lawmakers' demands are unlikely to stop the spending bill process. At the same time, no one knows for certain what will happen, as Congress has a couple more days to review things.

Friday was the original shutdown deadline. But to give negotiators more time, Congress agreed to extend it for five more days, to midnight Wednesday. They extended that deadline again -- to Dec. 22 -- to give lawmakers time to review the deal.

Even with all the deadline extensions, our experts are betting that the government is more likely than not to avoid a shutdown next week. Here's why:

[Ed. note: The Fix will be on shutdown watch until a deal is passed. If any of our experts' predictions change, we'll update this post, so bookmark it!]

Congress passed another short-term spending deal

Normally, this would be a bad sign. Congress practically lives on short-term spending bills, which carry over last year's budget to next year's. It's how they got to Friday's deadline, and it's what Congress ended up passing Friday instead of a two-year deal.

But this time, falling back again on a short-term bill could actually be a good sign, says Molly Reynolds, a governance expert at the Brookings Institution.

It signaled that lawmakers were close to a long-term deal and just need a little more time. (Sure enough, a deal was announced Tuesday.)

Broadcasting their imminent deal has had the potential effect of tamping down on some lawmakers' efforts to champion issues that could cause a shutdown: Why pick up a fight you know you're going to lose?

This spending debate is between Republicans and Democrats and not an intra-GOP fight

The sticking points that held up negotiators  are unlikely to resemble some of the intraparty fights that have caused or threatened to cause a government shutdown in the past.

That's because some issues — such as whether to raise the debt ceiling or how to deal with arbitrary spending cuts that grew out of a 2011 "fiscal cliff" — are already settled in the budget blueprint Congress passed in late October.

[The words you need to know during the shutdown debate]

Theoretically speaking* (see caveat below), all that was left for Congress to do is allocate dollars to the mission statements laid out in the budget.

There's a strong chance that conservatives won't be happy with what negotiators decided on: The budget on which the spending bill will be modeled was passed in the House with 187 Democrats and just 79 Republicans.

But party leaders know this, so they worked to ensure that what they come up with can get enough support from Democrats to carry the bill; in order words, they're trying to strike a good, old-fashioned bipartisan compromise. (Whether enough Democrats vote 'yes' to pass it is an open question as of Thursday.)

Lawmakers unhappy with the spending bill don't have a ton of tools at their disposal to stop it — except to start the whole process over again by trying to oust another speaker.

Our experts don't think conservatives are up to that this time around; they say there's enough goodwill among Republicans for their new speaker to let him try to pass a spending bill, even if it is supported mostly by Democrats.

Republican leaders really don't want a shutdown

Two budget experts The Fix spoke to said 2016 is weighing heavily on congressional Republicans' minds. The presidential election is just 11 months away, and the party's dream of being able to take back the White House after eight long years in the dark is within sight.

Right now, the issues being debated on the national stage — national security and terrorism — tend to favor Republicans. Why mess that up with a scene-stealing government shutdown under Republicans' watch?

"Republicans know they will own a shutdown," said former top Senate Democratic aide Jim Manley, "and that doing so will divert attention from Obama and his failed ISIS policies – their words not mine."

"Republicans have finally learned something," said Steve Bell, a former top Senate Republican aide and the director of economic policy at the Bipartisan Policy Center. "Shutting down the government is not good for their chances."

Ryan and Senate Majority Leader Mitch McConnell (R-Ky.) are hoping the rest of their party see the long game and get in line to pass this spending bill. Or at least not try to stop it.

But …

As always, we end any attempts to predict what's going to happen in Congress with a giant caveat.

And that is that anything could happen — any issue could suddenly become the issue and rally enough lawmakers to stop the entire carefully negotiated process in its tracks. (Few predicted refugee resettlement — once a nonpartisan budget item — would be as big an issue as it is today, for example.)

"The differences – and there are many – are about riders not money," said Maya MacGuineas, president of the bipartisan Committee for a Responsible Federal Budget. (Riders is D.C.-speak for political issues like Planned Parenthood or Syrian refugees; policy proposals lawmakers want to add onto the spending bill to limit or dictate spending on these particular issues.)

Congressional leaders might well have produced an agreement that enough lawmakers can live with to keep the government open.

But they can't control what forces will suddenly shift the political debate between now and then. And that's why our experts say a government shutdown was unlikely — but still can't be ruled out entirely.