Put simply, Republican Senate Majority Leader Mitch McConnell has not been a reliable dealmaker in recent months. Toward the end of 2017, he promised fellow Republican Senators Susan Collins and Jeff Flake a vote on bills that would stabilize the Affordable Care Act’s individual insurance markets and grant protections for Dreamers, undocumented immigrants who came to America as children and whose protected status President Donald Trump put into jeopardy last September. Neither promise has come to fruition, nor do they seem likely to.

Yet on Monday, most Senate Democrats backed a deal to reopen the federal government after a three-day shutdown based on a McConnell promise to open debate on legislation that would protect Dreamers if the government stays open past the next funding deadline on February 8 and no earlier deal materializes. Democrats balked at this offer on Sunday, then accepted it a day layer, and have since seemingly decoupled Dreamer and funding negotiations .

This about-face decision to apparently trust McConnell has enraged liberal Democrats, sewing the deepest divisions in the Democratic congressional caucus since the 2016 elections. Senate Minority Leader Chuck Schumer “has gotten so much blowback,” said legislative behavior expert Adam Ramey, “I wouldn’t be surprised if this leads to internal debate over his continued leadership.” So why did Democrats seemingly decide to trust in McConnell, despite his unreliable reputation?

One school of thought argues that Democratic leaders don’t actually trust him. They just needed an excuse to end a shutdown that, as legislative affairs expert Capri Cafaro put it, “did not end up being a strong negotiating tool.”

Democrats reportedly walked into the shutdown hoping they could get Trump to protect Dreamers in exchange for a few concessions, mainly border wall funding. But, as Cafaro pointed out, over the past couple of weeks Trump and the Republicans seemingly hardened their conservative stances on immigration. As the shutdown stretched on, Democratic leaders realized Republican messaging painting them as holding the government hostage for “illegal immigrants” could hurt their already vulnerable Senate electoral map this fall and might even sour chunks of the public on the Dreamers.

In this view, Democrats just had to get out of the bad spot they were in, even if it looked like a surrender to immigration activists and even if McConnell wasn’t telling the truth. If McConnell reneges on his promise, Democrats can just hit him over the head with that and use future funding bills as leverage to force another showdown if necessary. As Schumer reportedly hinted to dissenting progressive Senators after the deal passed, this may have been viewed the best of a series of bad options.

“This isn’t about a promise,” argued Congress watcher Joshua Huder. “It’s about leverage. Democrats have leverage. The promise is mostly fluff.”

Another school of thought on this deal, though, maintains that Democrats actually want to give McConnell the benefit of the doubt. He made the promise, the thinking goes, in a more public setting than his previous, broken promises. If McConnell follows through, that’s real procedural progress on an important issue. But if he reneges on this promise, after his previous failures to keep his word, it would likely lead to such a crisis of faith that, as Ramey put it, “the Senate, which has become increasingly dysfunctional, would grind to a halt.”

Ramey and other experts agree that McConnell is savvy enough of a politician to recognize these dynamics. Cafaro suggests that this is why he seemingly chose the wording of his promise extremely carefully, never guaranteeing more than to open up a conversation—essentially to extend more space for pre-existing negotiations.

“I don’t think McConnell’s going to go back on his word,” said Ramey. “And I don’t think he’s being insincere. But he knows whatever comes out of this is probably going to be minimal.”

On Thursday, details of the White House’s preferred compromise on immigration leaked out: In exchange for giving 1.8 million Dreamers a pathway to citizenship, Trump would want Democrats to agree to give him $25 billion for his border wall and other security projects and also slash legal immigration levels. That isn’t likely to draw much Democratic support, so chances are this won’t be the framework that makes it onto the Senate floor in February.

It’s not clear what sort of bill, if any, could make it to the Senate floor if McConnell keeps his promise. And even if the Senate came to a bipartisan deal on immigration, conservative hardliners in the House could kill it if they thought it was too generous, as they did with a moderate Senate immigration deal in 2013. House Republican leaders have already taken pains to make it clear they won’t feel bound to run with any legislation that stems from McConnell’s promise. And no bill can become law without Trump (and his cadre of anti-immigration aides) signing off on it.

“In short, McConnell’s promise is nearly irrelevant to… the odds of a deal,” said Huder. “Whether he is trustworthy or not is irrelevant.”

McConnell’s inability to control the House or Trump may be why, in the past, he has not made good on other promises. “Nobody wants to pursue a situation that ends up as a losing battle and causes greater acrimony, particularly amongst those in their own party,” explained Cafaro.

But McConnell might work to pass a bill this time anyway. “There may be a desire on behalf of the Senate leadership to pass the buck” when it comes to Dreamer protection legislation, said Cafaro, “by putting a bill on the floor, knowing that it will fail or die on the vine in the House, where both Democrats and Republicans have more pure, ideological views on immigration than their Senate colleagues.”

All told, there’s a good chance McConnell will come through on his promise—mostly because it’s not a promise to do anything other than allow debate and a vote on a bill of as-yet unclear substance that will likely get blocked by the House or Trump. Meanwhile, Democrats stand to lose face with their liberal base this November if Dreamer legislation stalls out again down the line despite their shutdown negotiation concessions for this promise.

Ultimately, this deal is not a referendum on McConnell’s trustworthiness. although it does stand to help his reputation on that front if he makes good on his promise. It’s more a reflection, regardless of the trust equation, of the tough spot Democrats found themselves in during the shutdown, McConnell’s strategic acumen, and the nihilistic and absurd state of congressional politics. When it comes to Dreamers’ fates and the shape of border security and immigration policy in America, none of this positioning really matters.

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