THE SKEPTICISM BEHIND THE OPTIMISM…. By late Wednesday, the odds of a government shutdown had suddenly dropped — a lot. There had reportedly been something of a breakthrough in the talks, and all of the relevant players were working around a compromise that would slash federal spending by $33 billion and avert a government shutdown.

You could almost hear the collective exhale from D.C. Widespread pessimism quickly turned into widespread optimism. Even on the Sunday morning shows, we’re hearing more hopefulness — Sens. Chuck Schumer (D-N.Y.), Jeff Sessions (R-Ala.), and Harry Reid (D-Nev.) all predicted this morning that policymakers will work out a deal and fund the government through September.

I certainly hope they’re right. Indeed, I’m heartened by the fact that everyone seems to realize they have an incentive to avoid a shutdown. As John Dickerson, who also seem confident that a compromise will come together, explained on Friday, “Despite all of the talk and threats of a government closure, both sides have always known that a shutdown would be disastrous for everyone.”

That’s true, but at the risk of raining on a parade here, there’s ample reason to believe failure remains an option.

With less than a week left before government funding expires, the rift between Republicans and Democrats on a budget agreement appears as wide as ever. […]

[The $33 billion] number has not been accepted by Boehner, who is facing a potential rebellion among more conservative members of his caucus who are pushing for more cuts. Michael Steel, his spokesman, told POLITICO the speaker “repeated to the president that there is no ‘deal,’ and he will continue to push for the largest possible spending cuts.”

The current deal to fund the government expires Friday, and despite hints that a new agreement was emerging last week, the two parties appear to be no closer to a deal to avoid the first government shutdown in more than a decade.

In fact, the White House readout said an administration “team” is working with congressional appropriators “to help reach resolution on the composition of those cuts,” signaling that Democrats are working off a number that Boehner has characterized as unacceptable to a large swath of his caucus.

I hope I’m wrong, but I’m counting the number of hurdles standing between right now and success before Friday night, and I’m not at all sure they can be cleared.

Here are some angles to consider:

* Matching the cuts to the target: As of Wednesday, the relevant players were working with the $33 billion target in mind for budget cuts. They weren’t even close to figuring out where these cuts would or could come from, and reaching agreement on this will be very difficult.

* House Republicans are kind of nuts: Even if Boehner strikes a deal, he’ll need votes from his own caucus. Roll Call reported yesterday that the Speaker’s own leadership team has told him the House GOP won’t go along with $33 billion in cuts. Rep. Tim Scott, a freshman member of GOP leadership. “You’d have to find a bill close to $61 [billion], or at least in the high $50 [billions].” (Remember, we’re dealing with lawmakers with the maturity of children — they’re obsessed with arbitrary numbers.)

* Boehner may eschew bipartisanship on purpose: The Speaker, if he can strike a deal, would need it to pass, but for now, he doesn’t actually want or care about Democratic votes. The AP reports this morning that Boehner “wants the overwhelming majority of those votes to come from his fellow Republicans, even if dozens of easily attainable Democratic votes could help carry the budget bill to victory.” It will be difficult enough to get to 218. If the Speaker cares more about which members help him get to 218, the challenge becomes that much more daunting.

* The “riders”: The GOP rank-and-file could probably live with $33 billion in cuts if they got more “riders,” but the White House and Senate Dems have already said these extraneous policy fights are deal-breakers. House Republicans may conclude they just can’t vote for a deal without the unrelated policy amendments, and Senate Democrats won’t vote for a deal with them.

* Tick tock: To avert a shutdown, a deal would have to be signed into law by Friday night. Even if policymakers act with surprising speed and efficiency, House Republicans have a rule that says they won’t vote for a measure unless it’s been posted for three days, giving members a chance to read it. Even if Boehner could agree to a deal and figure out a way to convince his caucus to support it, this compromise would have to be reached by Tuesday — two days from now — if he’s going to honor his own procedural rules.

Again, I appreciate the optimism and the fact that all of the relevant players seem genuinely eager to avoid a shutdown. But under the circumstances, I think it’s best to keep expectations low.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.