Late Monday, Senate leaders sounded optimistic that a bipartisan deal to reopen the federal government and raise the debt ceiling was close to fruition. "We've made tremendous progress," Senate Majority Leader Harry Reid (D-Nev.) said Monday evening. "We hope with good fortune... perhaps tomorrow will be a bright day."

Senate Minority Leader Mitch McConnell (R-Ky.), who came off the sidelines to start negotiating the deal with Reid over the weekend, agreed. "We've had a good day," he said, touting "substantial progress" toward an end to the fiscal standoff in Washington.

The centerpiece of the emerging deal is an agreement to finance the federal government until January 15 and raise the debt limit until about February 7. There would also be two minor changes to ObamaCare: A yearlong delay of a $63-per-person annual reinsurance fee temporarily imposed on employers and unions, and stronger verification requirements for people seeking government subsidies under the law. Finally, there would be a commitment to complete a long-term budget plan by mid-December.

The optimistic scenario for those who don't want the U.S. to default late Thursday is this: Reid and McConnell finalize the details on Tuesday and present the deal to their caucuses; the Senate approves the plan on Wednesday; and House Speaker John Boehner (R-Ohio) feels compelled to bring the bill up for a vote, passing it with a large number of Democrats and some portion of his own restive House caucus.

There are a number of potential pitfalls here that should be immediately obvious to anyone with even a passing interest in the current state of Washington. First, it would have to get out of the Senate. That's likely, considering the plan's parameters were hammered out by a bipartisan group of senators and Senate Republicans are getting increasingly anxious about how badly their party is faring in the polls. But remember, this is the Senate.

Justin Green at Businessweek says the Senate can push this package through pretty quickly, as an amendment to the "clean" budget bill it has already passed — but only if senators give unanimous consent. Any single senator, he notes, can gum up the works, sparking several 30-hour debate periods.

That means "Sen. Ted Cruz (R-Tex.), who basically forced the shutdown and whose own private polls have convinced him that it has been a glorious success, at this point could probably force a default and global economic calamity on his own," Green explains. Still, Cruz or any other senator could only postpone a vote until maybe Friday, no further.

The House, which could ignore or derail the deal, is the cause for real concern, however.

Boehner "provided no assurances on Monday that an arrangement hammered out by his Senate colleagues could pass muster among his conservatives," say Michael D. Shear and Jeremy W. Peters at The New York Times. Somewhat ominously, it's "already clear that the most conservative members of the House were not going to go along quietly with a plan that does not accomplish their goal from the outset of this two-week-old crisis: Dismantling the president's health-care law."

A deal with McConnell's imprimatur "may matter in some psychological or sense in terms of 'optics,'" says Slate's Matthew Yglesias. "But in the real world what matters is what the House GOP leadership wants to do." That means the fate of the economy is basically in Boehner's hands. That's not too reassuring, Yglesias adds. "So far throughout this crisis, Boehner and his team have put caucus unity ahead of the good of the economy."

"If Boehner allows a vote, the Senate deal likely passes the House" with a minority of House Republicans, says Paul Mirengoff at PowerLine. And this time he will probably waive the so-called Hastert Rule, especially if he can "extract another fig leaf or two" out of the Senate. The bottom line: "Right now, I think the Republican leadership in both houses just wants to stop the bleeding."

The great hope in Washington is that a bipartisan Senate deal will "'jam' the House and force its hand, with enough moderate Republicans joining with Democrats to pass the bill and avoid default," says David Graham at The Atlantic. "But the House, with its staunch band of GOP hard-liners, has been tough to count on for anything," and there's really nothing in the plan for the Tea Party faction but "a serious rout."

The main substantive outcome of the deal, though, would be that it kicks the budgetary can down the road. "Perhaps Republicans will have been so bloodied by this shutdown that they'll be reluctant to risk" another shutdown or debt-limit crisis, but they'll be playing on more favorable turf, Graham says. Still, the truth is that nobody seems to know what the House Republicans will do, and where exactly they're drawing their lines in the sand. Graham concludes:

That all adds up to a jittery few days. It's good news that things seem to be moving, but whether the thaw will prevent default and reopen the government is unlikely to be clear until just about the last moment. [The Atlantic]