Four freshman progressive House members are throwing a wrench into government funding negotiations, urging their colleagues to reduce spending on the Department of Homeland Security as a bipartisan committee negotiates a way forward for the agency.

“Cut, do not increase funding,” a bolded section of the “Dear Colleague” letter obtained by The Daily Beast reads. Authored by Reps. Ayanna Pressley (D-MA), Alexandria Ocasio-Cortez (D-NY), Rashida Tlaib (D-MI) and Ilhan Omar (D-MN), the letter is expected to be formally read on the House floor next week. “We have seen rampant spending on detention facilities for young children. The deal reached by the Conference Committee should not allocate any additional funding to this department or to the ICE and CBP agencies. The upcoming FY2020 budget process will be a critical opportunity to take up conversations about reforms to the agency. In the meantime, not another dollar.”

The letter arrives as a conference committee is attempting to reach a deal on border security that President Donald Trump would sign into law. DHS has been at the center of the fight over the president’s demand for a border wall and one of the committee’s tasks is to find a mutually-agreed-upon level of agency funding—and, within that, money for border security—before Feb. 15, when current funding for the federal government runs out again.

Up until now, the sticking point in these discussions has been whether or not the border security measures would include funding for Trump’s border wall. The freshmen progressives’ letter, however, indicates that they now expect more from Democrats than simply rejecting wall money.

“Our message is simple: we’re asking that Congress cut, not increase spending on detention facilities, stop using DHS as a slush fund, and include stronger accountability against DHS abuses under Donald Trump’s watch,” Omar told The Daily Beast. “We need to be the moral voice in calling attention to the abuses of ICE and CBP under Donald Trump.”

Additionally, the members who signed the letter are calling for the conference committee to “prohibit transfers and reprogramming authorities,” so as to prevent the Trump administration from using “DHS funding as a slush fund.” They also call for the final budget package to “be accompanied by stringent oversight mechanisms.”

The last new spending package for DHS, which laid out $47.7 billion in discretionary funds for the agency, was signed into law by the president in March 2018. That was a $3 billion increase in the agency’s budget from the previous year, Trump’s first in office.

“DHS must be held accountable, not rewarded, for its actions over the last two years, including family separations, barriers to asylum, and the deaths of two children in Border Patrol custody,” Pressley told The Daily Beast.

In releasing their letter now, the freshmen Democrats complicate an already sensitive and complicated negotiation process happening between the parties and congressional chambers. Democratic lawmakers on the conference committee indicated that plenty of options were on the table in talks with Republican counterparts. But decreasing funding for DHS was not one of them. The Democrats’ opening bid offers a $589 million increase in the agency’s budget from the year before.

The chair of the conference committee and the House’s top appropriator, Rep. Nita Lowey (D-NY), said Democrats are willing to expand on $1.6 billion for “border security” measures during negotiations with Republicans.

Democrats have proposed hiring 1,000 new customs agents and expanding Border Patrol aerial operations aimed at better securing the border, among other things.

Progressives were not the only ones trying to shift the center of the debate in their direction. Conservative allies of the president have called for the conference committee to give Trump more money for the wall than he has requested. Rep. Glenn Grothman (R-WI) said on Wednesday “I hope they realize that $5.7 billion isn’t enough. We need a wall.”

Despite pressure from their respective party flanks, conference committee members from both parties expressed optimism that they could reach a deal, even though, on Wednesday, they largely talked past each other on the specifics of the wall. Republicans affirmed that funding for “physical barriers” in “strategic places” was a necessary part of any compromise, and while Democrats insisted that all options were on the table, there clearly was little appetite to give in on any kind of new wall on the southern border.

The conference committee’s most progressive member, Rep. Barbara Lee (D-CA), called building a wall “useless and a waste of taxpayer dollars.”

“We must maintain our values as Americans as we address border security,” she said, “and building walls are antithetical to these values.”