After the recent scuttling of bipartisan bills on energy efficiency and expired jobless aid, the knotted-up chamber is reaching levels of gridlock that may make it impossible to score even legislative layups.

The next test of whether the Senate can do, well, anything comes on Monday when the chamber begins consideration of what would normally be a noncontroversial bill to reform the federal flood insurance program.

But feuding that began last November when Majority Leader Harry Reid (D-Nev.) made an unprecedented change to the Senate’s filibuster rules is intensifying into an utter breakdown of the amendment process that risks throwing low-level measures like the flood bill into limbo.

“We find ourselves at the end of this rocky road, and none of us like this location,” said Sen. Claire McCaskill (D-Mo.). “So we gotta figure out a way to get back up the road: It’s a dead end. A dead end means we do nothing, and our purpose here is we’re relegated to oversight only and not fixing things.”

It’s a fight that can make the Senate a less attractive place to work. With fewer committee bills considered before the full Senate and senators unable to get a vote on their amendments or stall nominations for political leverage, rank-and-file members are losing their influence — rapidly.

That has made it easier for senators to head for the exits rather than run for another term in a do-nothing Senate.

“It contributes a lot,” said Sen. Lamar Alexander (R-Tenn.), ticking off what he sees as premature retirements of GOP senators like Olympia Snowe of Maine and Mike Johanns of Nebraska, among others. “It’s a great honor, to be here but once you’re here, you want to do your job. And you can’t do your job if you can’t have a say.”

Republicans direct much of their ire at Reid, the hard-nosed majority leader who seeks to protect vulnerable Democrats from tough votes on hot-button issues like health care, the Keystone XL pipeline and abortion. More than any other leader before him, Reid has closed off the amendment process by an arcane procedural maneuver known as “filling the tree,” prompting howls of protest from GOP senators who complain they’ve been shut out of the process.

While Reid says he has no choice but to cut off amendment votes because Republicans will not deal with him in good faith, his strategy cuts both ways. When Reid closes off the consideration of amendments, ideas from Democrats are also stifled, preventing them from offering legislation they can tout to voters back home.

Sens. Mark Begich of Alaska and Mary Landrieu of Louisiana — two of the most vulnerable Democrats up for reelection in November — are among a growing group of senators frustrated over the amendment logjam. Begich griped that he couldn’t get a vote on changing military retirement pay, while Landrieu wanted a vote on job-training and skills development proposals on the Senate’s immigration bill.

“I believe as legislators that’s our job, and I’m one of those advocates that [believes] we should allow as much open amendments as possible,” Begich said. “But I’d also say it’d be nice if they’d be relevant.”

With the Senate voting on fewer than 10 amendments under regular order since July, each bill that comes before the chamber is eagerly eyed by hungry lawmakers hoping to get a vote on their political wish list. Members are now “starving” for a chance to offer an amendment that bears their name and political priorities, according to Sen. Joe Manchin, a party-bucking West Virginia Democrat.

“People say: ‘We don’t have many amendments, so we’re going to throw everything at you,’” he said. “And other people say, ‘I got you. I want you to vote on this so I can use this against you.’”

Manchin added, “[Reid] should be open to everybody’s amendments. … I’ve heard a lot about how the process used to work. I’d like to see it one time.”

Democrats and Republicans agree the Senate needs to consider more amendments on the floor. But they also agree that the meltdown is mostly the other party’s fault. It’s precisely that intractability that stands to derail nearly any legislation in the Senate not tied to a crisis like a debt default or government shutdown.

What makes the issue complicated is that the Senate operates on a principle known as unanimous consent — meaning any one senator can object to an amendment and effectively block a vote. When Senate leaders have tried to come up with a finite list of amendments to be considered on any given bill, the process often falters, namely because it requires the sign-off of all 100 senators, many of whom feel miffed over having their pet issue bypassed for a vote.

And while there’s no rule preventing irrelevant amendments from being offered, Democrats say that Republicans continue to bring forward proposals unrelated to the bills simply to score political points.

Public enemy No. 1 for Democrats is Sen. David Vitter (R-La.), who is widely blamed for scuttling the bipartisan energy efficiency bill last year that was destined for passage. Vitter demanded a vote on a proposal to slash Obamacare subsidies for lawmakers, Capitol Hill aides and administration officials. Reid refused to give the plan a vote and abandoned the bill over the impasse.

“That should have been motherhood and apple pie. And it got caught up in completely unrelated politics. And that’s the stuff that drives my constituents crazy,” said Sen. Martin Heinrich (D-N.M.), a freshman who has never received a vote on one of his amendments.

Majority Whip Dick Durbin (D-Ill.) said there can be some middle ground.

“There are two positions which I think are indefensible. One says no amendments, the other says unlimited: Let ’em bring hundreds until they get tired,” he said. “The responsible course is between those.”

Democratic leaders admit some culpability for the lack of amendment votes. But they also say Republicans have unrealistic expectations and hide behind procedural arguments to oppose legislation, including the jobless aid extension, rather than fighting on the merits.

“It’s the responsibility of leadership on both sides to say to members: ‘OK, we’ve got five, maybe 10 amendments. We’re going to have to choose some, all of them won’t make it this time,’” said Durbin, who works closely with Reid in negotiating a way forward on the Senate floor. “Anybody who’s brought a bill to the floor is going to have disappointed colleagues.”

The value of simply having a vote on an amendment cannot be overstated to some senators. Last year, when negotiators agreed to slip an amendment from Sen. Rob Portman (R-Ohio) into the sweeping immigration bill, Portman balked because he wanted a separate roll call vote on his proposal. But if Reid offered Portman a vote on the bill, he would have to offer votes to everyone else. The end result: Portman’s so-called e-verify plan didn’t get a vote, and he didn’t support the immigration bill.

Earlier this month, Reid embraced an altered version of Portman’s amendment to the jobless benefits bill that would prevent people from drawing both unemployment and disability benefits. But after Reid limited amendments on the bill, Portman dismissed it as a “take-it-or-leave-it” proposition from Democrats and ended up voting to block the unemployment bill over concerns about how it was paid for.

Democrats believe Republicans are viewing the Senate’s past through rose-tinted glasses, reminiscing of a chamber in which each senator once had equal heft and the ability to get any vote they requested on any bill.

“There was never a time as long I’ve been here where there’s been a completely open, completely unlimited, completely freewheeling amendment process. That has never existed,” said Landrieu, who has served since 1997.

Indeed, the procedural battles have essentially become an arms race in which each side copies the other and ratchets it up to the next level. Filibusters requiring 60 votes even to begin debate on legislation used to be uncommon, but now Republicans routinely threaten to use them. It was much rarer for leaders to block amendments, and now Reid does it on a regular basis.

And it was the GOP’s filibuster threats on judicial and executive nominees that prompted Reid to deploy the once-unthinkable “nuclear option,” changing the rules by a simple majority — rather than a two-thirds supermajority — in order to allow most presidential nominations to overcome a filibuster by 51 votes. Republicans warn they’ll do the same if they return to the majority — but potentially also on legislative filibusters.

Before last week’s recess, the final offer from Reid on the unemployment bill was to vote on amendments from each party that could win adoption only if they cleared a 60-vote threshold as long as Republicans agreed not to filibuster the bill on final passage. This was immediately dismissed by Senate Minority Leader Mitch McConnell (R-Ky.) and his caucus as a rule-bending offer they could never accept.

With Reid vowing to have another go at opening up traffic on the floor on the flood insurance bill, the measure’s backers, including Landrieu and Sen. Johnny Isakson (R-Ga.), are attempting to clear the deck as much as possible to shield the bill from controversy. They’ve enlisted Vitter as a co-sponsor to avoid yet another contentious fight over his Obamacare plan.

“I am not worried,” Landrieu said of the fate of her bill, before adding that the prospect of yet another tortuous amendment dispute that could tank her bill “has crossed my mind.”