Tester said he’s eager to see if a bipartisan group of negotiators can come up with an agreement on a policy issue as elusive as immigration. While he refused to commit to supporting a deal until he sees its details, he didn’t rule out backing stronger border requirements. And he’s not alone.

“I am certainly okay with [border policy] being a part of a national security supplemental,” said Sen. Tammy Baldwin (D-Wis.), another Democrat facing reelection next year. On changes to asylum policy, she said: “I would like to see us make some bipartisan progress, which has eluded us for years. The system’s broken.”

Efforts to rewrite the nation’s immigration laws have long been marked by failure, including a high-profile crater five years ago on border security and legalization for those protected under the Deferred Action for Childhood Arrivals program. And while there is movement among some Senate Democrats toward satisfying the key GOP demand that any aid for Ukraine and Israel be married with stricter border policies, others in the party are resistant.

Democrats probably wouldn’t even be considering this had Republicans not drawn a red line earlier this fall on linking the border with Ukraine. And so far, talks among Democrats and Republicans have centered around stricter asylum standards, with several Democrats saying they could support raising the bar for migrants to successfully claim asylum in the United States.

But the chief negotiators separately indicated Tuesday they’re not yet close to an agreement. The White House and Democrats are resisting changes to the humanitarian parole system, including forcing migrants to remain in Mexico or other countries while they await entry into the United States, according to a person briefed on the talks. And Republicans won’t allow Democrats’ priorities on undocumented immigrants known as “Dreamers” to be part of the discussions.

The Biden administration — which has requested nearly $106 billion in funding for Ukraine, Israel, Taiwan and the border— has maintained a hands-off approach to the bipartisan Senate negotiations. But officials have conveyed support for the talks. There is a broader recognition that the party’s support could wedge Democrats between immigration reform activists and independent voters.

Ultimately, Republicans say President Joe Biden will have to jump in to finalize a negotiation, particularly if the six-member Senate gang currently engaged in talks stalls out.

“I don’t mean to deprecate the people who are talking. But ultimately this is going to be a deal that’s going to be made between President Biden, Senate Majority Leader [Chuck] Schumer, Speaker [Mike] Johnson and Leader [Mitch] McConnell,” said Sen. John Cornyn (R-Texas).

Democrats are reluctant to tighten up the parole system because the Biden administration has used the program’s executive flexibility to admit migrants from Afghanistan, Ukraine, Venezuela, Cuba and other countries. And more broadly, progressives and immigrant rights groups argue Democrats are already giving into Republican demands without making any progress on their own immigration priorities, such as protecting DACA recipients or others brought into the country as children without documentation.

“Now is the moment for Democrats to stand up and make clear which priorities for immigrant communities are they fighting for,” said Andrea Flores, vice president for immigration policy and campaigns, FWD.us. “Or are they simply going to accept radically damaging changes?”

Sen. Alex Padilla (D-Calif.) said he’s working to get a pathway to citizenship added to the negotiation, although Republicans have said that’s a non-starter. Still, he refused to rule out supporting changes to the asylum standard. “The devil is in the details,” he said.

Like other vulnerable Democrats in cycle next year, Sen. Sherrod Brown (D-Ohio) also said he was open to including border security policies if that’s what it takes to unlock money for Ukraine and to combat the fentanyl epidemic.

But progressives may be less open to border restrictions.

The politics, said Sen. Dick Durbin (D-Ill.), “will be good for some and not for others.”

So far, there’s not a ton for the left to be happy about. And the GOP rejection of Democrats’ immigration priorities and insistence that Democrats go beyond just raising asylum standards has some Democrats’ gloomy on the prospects.

“I certainly fear that Republicans are having a hard time taking yes for an answer. But we’ll continue to work,” said Sen. Chris Murphy (D-Conn.), the Democrats’ chief negotiator.

Still, the narrow 51-member Democratic majority can’t make a move without at least nine Republicans given the Senate’s 60-vote requirement. Many Senate Republicans support more funding for Ukraine but they seem intent on using their leverage, in part in a bid to create a bill that Speaker Johnson might take up in the House.

McConnell, an old friend of Biden’s, said he called the president last week “to make sure he understood that there wouldn’t be a bill without a credible effort” to restrict the flow of migrants to the southern border.

But that position boxes Democrats in: To get Ukraine aid, they must forge an agreement on the extremely touchy issue of immigration.

“There are some people who have said that there is no progress that can be made on Ukraine without an agreement on the border,” said Sen. Michael Bennet (D-Colo.), one of the six negotiators.

Asked about raising the asylum standard, Schumer declined to answer directly and simply said “we need a bipartisan bill.” He plans to force a vote as soon as next week on the Biden administration’s entire $106 billion supplemental spending request, which Republicans say they will block without the inclusion of tough new border policy restrictions.

“We probably have to do that to demonstrate to Democrats who may be wondering about the resolve among Republicans on this issue,” said Sen. Thom Tillis (R-N.C.).

Should a vote fail, it would further prolong the amount of time since Congress last approved Ukraine aid late last year. And without a government funding deadline until January, the Senate will have to put together a holiday surprise pretty quickly to signal to Kyiv that more aid from the U.S. is coming.

Myah Ward and Anthony Adragna contributed to this report.