The prevailing view: When Congress returns in September, sabers will be rattled and threats will be hurled. But then, as usual, Washington will grind out a crummy deal that keeps the federal lights on and avoids a disastrous default.

“D.C. always gets very close to the edge and then in the end finds an eleventh-hour solution,” said Jan Hatzius, chief economist at Goldman Sachs. “It seems hard to believe that we are going to have a really big problem”

But this time — wait for it — could be different. Really, seriously different.

( WATCH: Obama’s full Friday press conference)

Here is just a sampling of why Wall Street may be wrong: The House GOP is hopelessly fractured on spending strategy. Senate Republicans who might otherwise broker a deal face primary challenges that make compromise potentially deadly. Other Senate Republicans are jockeying for 2016. And congressional Democrats have no appetite for any bargain — grand or otherwise — that cuts entitlement spending.

President Barack Obama at his Friday news conference before leaving for vacation lectured Republicans and mocked their threats to shut down the government rather than fund his signature health care law. Hardly a promising sign for the fall.

“The idea that you would shut down the government at a time when the recovery is getting some traction …,” Obama said, “I’m assuming that they will not take that path. I have confidence that common sense, in the end, will prevail.”

( Also on POLITICO: McConnell demands unity on fiscal issues)

And it is not just a government shutdown or debt-ceiling crisis that could cause a Beltway shakeup of markets this fall.

There is also the possibility of a nasty confirmation fight for the next chairman of the Federal Reserve just as the central bank starts to wind down its program of buying hundreds of billions in bonds to support the economy.

Wrap all this potential dysfunction together and there is a real chance that the fall of 2013 will be more like the summer of 2011, when a near-miss on the debt ceiling led to a ratings agency downgrade, a huge sell-off in the stock market and yet another hit to an economy that might otherwise be heating up nicely.

“There’s going to be some pain that isn’t being priced into market expectations,” said Compass Point Research & Trading analyst Isaac Boltansky. “Right now the markets are doing well, but I don’t think it’s pricing in this impending battle.” Or battles.

( Also on POLITICO: Obama: No shutdown over ACA)

Leadership in both parties seem to want a continuing resolution in September that would fund the government through the end of the year. They may get it. But it’s not obvious how. And even if they do, raising the debt ceiling is a much bigger and potentially more damaging hurdle. Comments from lawmakers as they left town for August suggest how difficult it will be.

“[As] the condition of raising the debt ceiling, we absolutely should insist on spending restraints,” Sen. Pat Toomey (R-Pa.) told POLITICO. “On the other side there’s an effort to try to minimize the magnitude of the fiscal challenge that we face because the deficit has gotten a little smaller in recent years. We shouldn’t be lulled into a false sense of complacency. We still are on a completely unsustainable fiscal path.”

( Also on POLITICO: Romney warns of shutdown)

GOP Sens. Marco Rubio of Florida and Ted Cruz of Texas, perhaps with an eye on the 2016 presidential race, are demanding that Senate Minority Leader Mitch McConnell block any spending bill that funds Obama’s health care law as enrollment begins Oct. 1. There is no chance Obama would sign a spending bill that takes money away from implementation of his biggest achievement.

Meanwhile, McConnell and Sen. Lindsey Graham (R-S.C.), who might otherwise help push a fiscal compromise, face 2014 primary challenges that may make them less likely to cut deals with Obama. McConnell has been pivotal in recent battles, including the fiscal cliff deal his office hammered out at the last second with Vice President Joe Biden at New Years. Don’t expect a replay this fall.

On top of all this, McConnell and House Speaker John Boehner recently lost several top backroom negotiators to the private sector, making a path out of the current stalemate even tougher.

Former GOP presidential nominee Mitt Romney grew so concerned over rhetoric from Rubio, Cruz and others that he used his first significant post-2012 speech to urge Republicans to back down from the government shutdown rhetoric.

“We need to exercise great care about any talk of shutting down government,” Romney said at a fundraiser in New Hampshire on Aug. 6. “What would come next when soldiers aren’t paid, when seniors fear for their Medicare and Social Security, and when the FBI is off-duty?”

Then there is the matter of the House GOP, which had to pull a $44 billion housing and transportation funding bill from the floor this month because conservatives thought it spent too much and moderates thought it spent too little.

And even if the two parties find a path past Oct. 1 and avoid a government shutdown, raising the debt ceiling will be no easy task. Republicans have not backed off their mantra of a dollar in spending cuts for every dollar of debt-ceiling increase. But if they were to pass such a bill out of the House, it would go nowhere in the Senate. Democrats have no appetite for more cuts, given that annual deficits have been sliced in half and the sequester spending cuts are already taking a bite out of economic growth with no compromise on the horizon.

“It’s not negotiable. It should be done,” said Sen. Sherrod Brown (D-Ohio) of raising the debt ceiling. “Business everywhere believes that this is a bad thing for the country. The Republicans, they call themselves the pro-business party. They should act that way.”

The White House is also likely to stick hard to its vow not to negotiate over the debt ceiling.

Should Washington grind to a halt this fall, it would come once again as the economy is on the cusp of a period of stronger growth. Many forecasters believe that once the drag from the sequester spending cuts and tax increases fades later this year the economy is capable of growing at 3 percent or faster and creating 300,000 jobs a month or more rather than its current pace of under 200,000.

Housing prices and equity markets have been rising, small businesses are showing more inclination to hire and spend, and threats from Europe are receding, leaving D.C. dysfunction as among the top remaining risks.

“There’d be a host of severe economic consequences associated with debt default. We’d have negative impact for growth, job creation, interest rates would spike, it would make our deficit problems even harder to tackle,” said Rob Nichols, president and CEO of the lobbying group Financial Services Forum. “Raising the debt ceiling is a critical and urgent task.”

Adding to all the risks is the fact that the fiscal fights will come just as the Fed is expected to begin slowing its monthly asset purchases, which have been keeping interest rates low and boosting stock prices. The consensus on Wall Street is that the so-called taper of asset purchases will begin in September. Markets have been rocked in the past by the mere mention of a cut in asset purchases, making this fall a scary time for the central bank.

And that’s not all. The taper is likely to begin just as Obama makes his choice for Fed Chairman Ben Bernanke’s successor. Any candidate is likely to face blowback from Republicans unhappy with what they view as central bank activism that risks higher inflation and asset bubbles.

But things could get especially heated if Obama nominates former Treasury Secretary Larry Summers, who is beloved inside the White House but draws ire from many liberal Democrats who would rather see the president pick Fed Vice Chairwoman Janet Yellen.

A messy fight over Bernanke’s successor could turn into the worst of the Washington battles because it would generate uncertainty at a critical moment for the central bank. That could in turn drive interest rates higher and choke off economic growth.

“If it’s noisy enough to make it seem as though the president might not get his nominee through, that could cause quite a large reaction in the market because the direction of Fed policy is so important right now,” said Hatzius.

All this means that the sequel Wall Street expects this fall could turn into a much scarier movie with unpredictable plotlines.

“None of them individually are game changers for the market,” said Boltansky. “But when you add all of them together, they suddenly become a concerning story.”

White reported from New York; Lee from Arlington, Va.