Members of Congress from both sides of the aisle vowed Tuesday to pass legislation to undo President Donald Trump’s decision to terminate the Deferred Action for Childhood Arrivals (DACA) program. But with a GOP-controlled Congress that has proven itself barely able to keep the basic gears of government turning this year, advocates and political veterans are taking these promises with a large grain of salt.

“It’s not easy and it’s probably not realistic,” said Doug Heye, who was a top adviser to then-House Majority Leader Eric Cantor (R-VA) during Congress’ last attempt at comprehensive immigration reform — when House Republicans’ fear of their base killed the effort. Heye said the same forces that tanked reform in 2013 have only “calcified” since, with Republicans fearful both of their own base (and rightly so, given Cantor’s shocking 2014 primary defeat was driven in large part by his support of immigration reform) and of Trump.

So despite calls from the White House, the Republican speaker, several rank and file Republicans, almost every Democrat on Capitol Hill, the business community and a host of religious groups for Congress to find a way to keep the 800,000 undocumented immigrants brought here as children from facing deportation or being forced back into hiding, chances are slim that Congress will be able to pass anything to protect the young immigrants by the time their DACA protections expire six months from now.

In one ominous sign for the chances of Congress passing a DACA fix, Senate Majority Leader Mitch McConnell (R-KY) did not mention the issue at all in his first post-recess speech Tuesday afternoon.

The White House has also shown no leadership on what kind of fix it wants, and instead has simply threatened Congress to get something done.

Asked Tuesday if Trump would support a standalone bill to restore DACA, White House Press Secretary Sarah Huckabee Sanders would not answer outright, but hinted that he expects strings attached to any DACA bill—in the form of more money to crack down on undocumented immigrants or funding for a border wall with Mexico.

“We can’t just have one tweak to the immigration system. We need really big fixes,” she said.

Trump himself didn’t speak on the issue at all until hours after the announcement, flippantly telling reporters during an unrelated afternoon event on tax reform: “Hopefully now Congress will be able to help them and do it properly.”

Then, Tuesday night, Trump appeared to reverse his threat, taking all the pressure off Congress to act.

Congress now has 6 months to legalize DACA (something the Obama Administration was unable to do). If they can't, I will revisit this issue! — Donald J. Trump (@realDonaldTrump) September 6, 2017

With lawmakers facing an already-packed autumn in which it has to raise the debt ceiling, keep the government funded and find billions in aid for Hurricane Harvey victims, it’s unclear when they’ll be able to tackle an issue that has stymied lawmakers for years—with no clear direction from the White House.

“It would be helpful if he would say, ‘I’ll sign the DREAM Act, or I’ll sign the SAFE Act,” Sen. Jeff Flake (R-AZ) told reporters Tuesday, ticking off various immigration bills currently floating around the Senate. “I want to hear him say what he’ll sign.”

Bipartisan efforts to save the program began burbling in both chambers of Congress weeks ago, as it became clear Trump was leaning towards ending DACA. On Tuesday, they kicked into overdrive. Just a few hours after Attorney General Jeff Sessions broke the news, Sens. Dick Durbin (D-IL) and Lindsey Graham (R-SC) held a press conference on Capitol Hill to promote their DREAM Act — a bill that would go beyond reinstating DACA by giving that population a path to citizenship.

But even during this display of bipartisanship, conflicts emerged, with big questions about whether Republicans would insist on attaching a DACA fix to more funding for an immigration crackdown, and whether Democrats could stomach that deal.

Graham blasted DACA as “unconstitutional overreach” by the Obama administration, and insisted the DREAM Act would eventually be just one piece of a comprehensive immigration plan that includes border security funding and stricter immigration checks through the E-Verify system. Durbin, who has been trying to pass a DREAM Act for 16 years and strongly backed Obama’s creation of the program, said the DREAM Act should pass on its own merits, and called funding for a wall with Mexico a “non-starter.”

While Durbin mocked a reporter’s skepticism that Congress could pass a bill at all — “Some people look at a donut and just see a hole,” he lamented — Graham admitted how disconcerting it must be for those with DACA status to have to rely on an unreliable Congress.

“The only thing that stands between you and certainty in your life is the Congress,” Graham quipped. “That cannot be that reassuring.”

Sen. John McCain (R-AZ), a longtime supporter of the DREAM Act, was even more pessimistic, saying bluntly that he does not know if Congress can pass a bill before the six-month deadline.

Many Republicans, including Ryan, signaled they’ll only support a plan that secures more money to implement Trump’s crackdown on immigrants and border wall in exchange for protecting the DACA population—a position Democrats and immigrants’ rights advocates are flatly rejecting.

“We are demanding standalone legislation with no strings attached, no criminalization, and no money for the wall,” Cesar Vargas, the co-director of the Dream Action Coalition and himself a DACA recipient, told TPM. “We will not start from a position of weakness in this negotiation.”

Cristina Jimenez, the head of United We Dream and another DACA recipient, told reporters on a conference call that “it’s a nonstarter to have a conversation about tradeoffs” for funding for programs like more immigration and customs agents that “will get my parents detained and deported.”

Members of the Congressional Hispanic Caucus outwardly expressed similar views, though some privately said they were beginning to discuss amongst themselves and with outside advocates what hard choices they might be willing to make to protect DACA recipients.

On the GOP side, even lawmakers who expressed optimism they could clean up Trump’s mess said they were unsure whether House Speaker Paul Ryan (R-WI) would be willing to bring a bill to the floor without the support of the majority of GOP lawmakers. And they warned that the closer it came to primary season, the more difficult it could be for lawmakers.

“The earlier the better, because as it goes a little bit later, then it’s [candidates’] qualifying period and then it gets a little trickier,” Rep. Ileana Ros-Lehtinen (R-FL) told TPM.

With precious few legislative days for a dysfunctional Congress to reinstate a program nearly every Republican previously opposed, Republicans aren’t feeling optimistic about its chances.

“This could blow up on the legislature,” warned former Rep. Tom Davis (R-VA), who chaired the National Republican Congressional Committee during his time in Congress. “So far Congress has failed every test they have but maybe they study hard for this one and realize their backs are against the wall.”

Still, lawmakers on both sides of the aisle insist that despite the time crunch, despite the deep divisions in the GOP on immigration, and despite the complete lack of direction from a mercurial White House, they can somehow come together before DACA recipients come under threat of deportation next March.

“Hope springs eternal, how about that?” Sen. Ron Johnson (R-WI) said with a laugh. “People have been working on this for a long time. Maybe this is the catalyst that actually results in some action.”

This story was updated at 7:30 p.m. EST.