Tonight is the night that all 535 of America's lawmakers have been dreading...

In keeping with his promise to call an open-ended debate on an immigration compromise bill should lawmakers fail to reach a compromise on their own, the Senate tonight will begin arguing about a bill that has no clear form or substance...

Senators are predicting a chaotic debate, according to the Hill. Tonight, Majority Leader Mitch McConnell will call for debate on a shell bill that basically will allow lawmakers to bringing up any and every topic they'd like. And predictably, several different factions are working out their own plans, all hoping to be the leaders of the eventual compromise bill that makes it to President Trump's desk.

“It sounds like Senator McConnell’s just going to pull up a shell bill and let people have at it. ... It ought to be pretty fascinating,” said Senate Majority Whip John Cornyn (R-Texas), McConnell’s top deputy. Sen. Dick Durbin (Ill.), Cornyn’s Democratic counterpart, predicted: “You’re going to hear as many variations as the fertile minds of my colleagues can produce.”

McConnell made his promise to secure the necessary Democratic votes to pass the bipartisan agreement to keep the government funded through March 23 while raising the debt limit and suspending spending caps that will open the door toward negotiations for a two-year budget deal.

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So far, lawmakers have complained that the White House - which is ostensibly pro-DACA - has repeatedly shifted its position, making it impossible to negotiate or arrive at anything even remotely resembling a compromise that would be acceptable to Democrats.

For example, the so-called "Gang of Six" famously put forward a bipartisan proposal that included enshrining DACA protections in exchange for increased funding for border security - but crucially, it didn't include money for the wall, and so was panned by President Trump.

Another group led by Maine moderate Susan Collins is calling itself the "Common Sense Coalition". They're focusing on a narrower solution than the "four pillars" that Trump and a group of bipartisan lawmakers reportedly agreed upon a few weeks ago. Those include: Wall funding, changes to family-based immigration and the visa lottery system, funding for border security and DACA protections.

But in a deliciously ironic twist, the Common Sense group says it has already begun drafting legislation, even though it hasn't finished working out the compromise. All Collins could say was that they've agreed to focus exclusively on two of Trump's coveted four pillars...

This group of more than 20 senators, led by Susan Collins (R-Maine), has begun drafting legislative text. But it still hasn’t reached a consensus about what it could support. “I think we’re getting pretty close on coming up with a proposal that may or may not be offered next week,” Collins told reporters after the group’s last closed-door session. “There will probably be more than one [amendment offered] but it’s too early to tell right now.” Senators in the group have focused on a narrower solution that would break from the “four pillars” strategy that Trump and a bipartisan group of lawmakers initially agreed to.

Some members would like to issue a broader proposal - but they worry the more they try to tack on, the harder it will be to pass.

Members haven’t ruled out trying to broaden their proposals, but warn that the more they try to tack on the harder it could be to get a bill that can pass the Senate. "If we can stay focused on those two, I think we can get to 60. The challenge is there are lots of other problems that both the White House and other members want to do," said Sen. Christopher Coons (D-Del.), a member of the group.

Another divide is that some Democrats are continuing to fight for protections to be extended to the parents of so-called "Dreamers." Many GOP lawmakers are wary of granting protected status for people who entered the country illegally, which could give them an advantage over immigrants who entered the United States at the same time.

Amidst the chaos, Trump has continued to blame Democrats over the weekend for the the inability to get a DACA deal, saying they would rather "use it as a campaign issue."

Republicans want to fix DACA far more than the Democrats do. The Dems had all three branches of government back in 2008-2011, and they decided not to do anything about DACA. They only want to use it as a campaign issue. Vote Republican! — Donald J. Trump (@realDonaldTrump) February 10, 2018

Despite the flurry of closed-door meetings and the variety of plans that are gestating, lawmakers remain divided and there's still unclear how the Senate will manage to pass a bill before the March 5 deadline - to say nothing of the House, per Politico.

That's because Speaker Paul Ryan has insisted he will only bring up a bill that is supported by Trump, who has repeatedly shot down compromise plans. That stirs up uncomfortable memories of a 2013 comprehensive immigration bill passed the Senate only to die in the House without ever receiving a vote.

Given that the debate over a permanent solution is so fraught, at least one lawmaker - Sen. Jeff Flake - is working on a backup that will extend DACA protections for three years while also increasing border security funding.

Indeed, in a rare burst of honesty, Sen. Lindsey Graham joked that he hopes Congress can pull a “white rabbit out of its hat” but predicted that the most likely outcome is kicking the fight down the road.

"If I were betting man … I’d always bet on Congress to punt," he said. "I just hope we don’t punt on first down. I hope we at least go to fourth down before we punt."

We wouldn't take the other side of that bet...