The unexpected flare-up of partisan rancor over a minor line-item in the federal budget this week left lawmakers feeling increasingly gloomy about their ability to address issues of greater consequence, from the stubbornly high jobless rate to the soaring national debt.

“It’s a lot of energy wasted for nothing,” Rep. Phil Roe (R-Tenn.) said Friday as the Senate rejected a House-passed bill to fund the government for the next few weeks. “If we can’t do this, how do we do the heavy lifting?”

Congress left town for the weekend without resolving the latest spat over spending, an almost accidental dispute that set the parties bickering over $1.6 billion in budget cuts — an amount that equals just 0.04 percent of the federal budget. As a result, Washington once again finds itself a week away from a potential government shutdown, a possibility that was supposed to have been averted as part of last month’s deal to end an epic battle over the federal debt ceiling.

That agreement was still largely intact Friday. But Democrats decided to pick a fight over a side issue: an insistence by the GOP to pay for more disaster relief funding by cutting a popular auto-industry loan program. Republicans refused to back down.

Outside analysts joined lawmakers in voicing despair about the prospect that such a bitterly divided legislature would be able to agree on a new jobs bill or another big round of deficit reduction, even as the global economy teeters toward fresh trouble.

“You have to wonder what comes out of the supercommittee that passes both houses of the Congress — and that’s a whole lot more complicated than keeping the government open for another few weeks,” said Sen. Roy Blunt (R-Mo.), referring to the special panel created during the debt-limit debate to slice an additional $1.5 trillion from future government borrowing.

Blunt said he has long believed that “the country is essentially in almost a holding pattern” until November 2012, when voters will have to decide what direction they want government policy to take. Until then, he said, “I’m not overwhelmingly optimistic” that Congress will be able to get much done.

The latest fracas appears to have snuffed out a fragile sense of comity that blossomed in Congress in the wake of the debt-limit debacle. Polls showed that voters were appalled by what they viewed as a naked display of political brinksmanship that risked destabilizing the U.S. economy.

In a memo circulated widely on Capitol Hill, GOP pollster Bill McInturff warned that the debt-limit debate had “shattered confidence in our political system and everyone involved.” Voters lost faith in the ability of both President Obama and congressional Republicans to “make the right decisions about the economy,” the memo said. But congressional Republicans had taken the bigger hit, it added, with 81 percent of those surveyed saying they had little or no confidence in the judgment of the GOP.

Anxious about Congress’ plunging approval ratings and the real-world market reaction to August’s tumult, lawmakers sought to repair the damage when they returned to work at the beginning of September.

House Speaker John A. Boehner (R-Ohio) politely offered to consider Obama’s ideas for creating jobs. And Boehner forged agreement with Senate Majority Leader Harry M. Reid (D-Nev.) on two pieces of long-stalled legislation, sending major highway and aviation bills to the White House for the president’s signature last week.

Even negotiations over the stopgap measure to fund the government into the new fiscal year started out well. The current measure funding the government expires next Friday, and lawmakers need more time to draft a far-reaching bill to finance federal agencies through September 2012.

As part of the debt-limit agreement, both sides agreed to cap next year’s agency spending at $1.043 trillion. Despite pressure from conservatives to renege on the deal and cut more deeply, Boehner held firm.

But then a dispute emerged over how much to increase FEMA funding and whether to offset the cost, and Congress began backsliding into gridlock. Veteran political analyst Charlie Cook, editor and publisher of the Cook Political Report, said if lawmakers continue down this path, the 2012 election could bring “the biggest, broadest anti-incumbent year of post-war history,” with voters indiscriminately tossing out lawmakers in both parties, pulling the lever “against anybody’s name they recognize.”

“The debt ceiling debacle is almost a horrible metaphor: It’s as if a bomb went off at 800 Pennsylvania Avenue and sent shrapnel flying in every direction,” Cook said. “I don’t know what these guys think they’re doing, but it looks like they’re committing political suicide.”

It was unclear how congressional leaders hope to break the latest impasse. Most departed from the Capitol early Friday afternoon with no plans for weekend negotiations. Instead of trying to reach agreement, both sides were mapping out strategies for blaming the other side if the government shuts down or, more likely, if FEMA disaster funds run dry Tuesday.

“You saw the House act,” House Majority Leader Eric Cantor (R-Va.) told reporters. “We are intending that the money gets to FEMA and to disaster victims as they need it.”

Cantor said it was entirely up to Reid to pass the House bill or “to bear the burden of denying disaster victims the money they need.”

Reid, meanwhile, rejected the notion that Democrats were to blame, noting that the Senate had approved a separate measure — supported by 10 Republicans — to increase FEMA funding without offsetting spending cuts.

“We’ve done our job,” Reid said. “So I don’t understand how anyone could suggest that anyone is at fault other than the Republicans in the House and the Republicans here in the Senate.”

Staff writer Paul Kane contributed to this report.