(Bloomberg) -- Senate negotiators said differences persist over US-Mexico border policy, stalling long-term legislation to fund the US government with lawmakers set to leave Washington at the end of the week.

At stake in the impasse between Republicans and Democrats is further US military aid to countries including Ukraine, which President Joe Biden’s administration says is needed to turn back Russia’s invasion. 

“We are still in the room trying to deal with Republican demands,” lead Democratic negotiator Senator Chris Murphy said on NBC’s Meet the Press on Sunday. “Right now, Republican demands are unreasonable. They don’t actually get Democratic votes.” 

As Republican hard-liners in the House demand tough provisions for securing the southern US border, Biden said last week he’s willing to make “significant compromises” to fix a “broken” system. 

The House Freedom caucus last week called for “significant and verifiable improvement” in US border security as a condition for aid to Ukraine, saying it would use “all available leverage” to change the status quo. Several GOP lawmakers said Thursday there’s no chance of passing Ukraine aid this year.

Murphy said Sunday that “some pretty big differences” remain between the two parties. “I think the White House is going to get more engaged this week,” he said on NBC.

Approaching in the new year is yet another funding deadline which would shut down some federal agencies if Congress fails to reach a broad agreement to fund the government before Jan. 20.

Republican negotiator Senator James Lankford said the Biden administration isn’t focused enough on tightening asylum rules.   

“Right now there’s been no consideration in the White House of how do we actually manage the capacity issues that are there,” Lankford said on CBS’s Face the Nation. “They seem to be focused on how many people can we just release into the country and tell them we’ll do a hearing sometime later.” 

Democrats and the Biden administration have warned for weeks that holding up the president’s request for $106 billion in emergency funds, which includes arming Israel and Ukraine as well as border security proposals, plays into the hands of US adversaries.   

“If we fail, if Republicans don’t get reasonable in the next 24-48 hours, Russia is going to march into Ukraine, China is going to be given a green light to invade Taiwan,” Murphy said Sunday. “The United States’ security is at risk.”

Secretary of State Antony Blinken said he’s “very concerned,” about Russia taking advantage of the gap in US funding to Ukraine. “We need to see this supplemental budget request go through as quickly as possible,” he said on ABC’s This Week.

“We’re not going to solve the entire problem of immigration between now and the end of the year, but we can make a down payment,” Murphy said.

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