Democrats are rejecting a backup proposal to temporarily fund the government if a broader border security deal falls through.

A senior Democratic aide said Monday that Democrats will not agree to a yearlong spending bill to keep the Homeland Security Department funded because Democrats believe it would allocate too much money for Immigration and Customs Enforcement, and too much money for barriers along the southern border.

The opposition to such a plan might make it even more difficult for Congress to meet a Feb. 15 deadline to agree to some kind of spending deal that includes border security funding. Republicans are pushing for even more border security spending, including funds for a border wall, in the ongoing talks.

But with little progress in those talks and Democratic threats to spike the level-funding backup plan, the chances are rising again that a partial government shutdown will happen at the end of this week. With no deal by Friday, dozens of agencies and nine departments would partially shutter for the second time this year.

Democrats are saying specifically that they can't agree to a continuing spending resolution unless it puts more limits on funding for ICE and a border barrier.

“A so-called ‘clean’ full-year CR for Homeland Security would allow the Trump administration to increase funding for both physical barriers and ICE detention beds,” the Democratic aide said.

Democrats want to limit ICE detentions to 16,500 between now and the end of the fiscal year, which is Sept. 30. That’s now a major sticking point in the bipartisan talks among lawmakers seeking a border security funding deal.

Democrats want to cut the number of detention beds, which would prevent ICE from holding detainees.

“Under a full-year CR, the Trump administration would fund ICE adult detention beds at a level of 46,000 or even higher,” the aide said. “In contrast, in conference negotiations, Democrats and Republicans had narrowed down the potential funding level for ICE to a range that would require ICE to ramp down the number of detention beds to between 34,000 and 38,500 by the end of the year.”

The aide said the Trump administration also believes it would be able to use $2 billion in the CR for physical barriers along the U.S. Mexican border.

“An acceptable compromise will fund border security without being overly reliant on physical barriers, and will include curbs on the Trump administration’s cruel immigration policies,” the aide said.

On Monday afternoon, a group of bipartisan negotiators were huddled in the Capitol, attempting to revive talks that stalled after Democrats insisted on capping ICE detentions.