WASHINGTON — House Speaker Mike Johnson told fellow Republicans on Tuesday that sweeping changes to U.S. border policy would be their “hill to die on” in negotiations that have already grown tense as Congress considers President Joe Biden’s $110 billion package for the wars in Ukraine and Israel and other security needs.

Johnson delivered the hard-line message Tuesday morning ahead of classified briefings the Biden administration organized to underscore how desperately the aid is needed. Ukrainian President Volodymyr Zelenskyy was scheduled to address the senators via video but had to cancel his appearance, Senate Majority Leader Chuck Schumer said.

Instead, the meeting erupted in frustration and yelling as Republicans insisted on including border security in the discussion.

Democrats have dismissed the Republican border proposals as attempts to return to the draconian policies of former President Donald Trump.

Biden is pushing a reluctant Congress to approve the military, economic and humanitarian aid package, but the injection of border security into the negotiations has made progress difficult.

The Senate was headed to a test vote Wednesday, but Republicans have promised to block it.

“The battle is for the border,” Johnson said at a news conference. “We do that first as a top priority, and we’ll take care of these other obligations.”

Moments earlier, Johnson told GOP lawmakers in a closed-door meeting that their “hill to die on” in the negotiations was border policy, according to a Republican in the meeting.

Conservatives are pressing for the provisions in H.R. 2, a bill they passed in May that would restart construction of walls along the southern border and make it drastically more difficult for migrants to claim asylum in the United States.

Johnson reiterated his stance in a letter to the White House on Tuesday, one day after officials warned that the U.S. will run out of funding to send weapons and assistance to Ukraine by the end of the year, threatening its ability to fight Russia’s invasion.

In the Senate, Schumer was pushing toward a test vote Wednesday on the emergency funding for Ukraine, Israel and other national security needs, but without the border provisions Republicans are demanding.

He described the package as crucial to ensuring the future of Ukraine and democracy.

“This is a turning point in Western civilization,” Schumer told reporters at a news conference.

Schumer added that Johnson told him in a private meeting that he could not pass the supplemental package through the House without H.R. 2 attached.

The GOP’s demands could imperil any legislation that emerges from the Senate, where a bipartisan group is trying to find agreement on a pared-down set of border policy proposals.

Republicans in those negotiations have acknowledged they are not insisting on the broad policies included in the House’s legislation.

The Senate negotiations have centered on a proposal to raise the initial threshold for migrants to enter the asylum system, as well as limiting the executive branch’s ability to admit migrants through humanitarian parole.

Before the test vote, Schumer made Republicans what he called a “golden offer”: If they agree to move ahead with the aid package, they could offer any amendment they want to add on border security.

But Senate Minority Leader Mitch McConnell, R-Ky., showed no interest and is encouraging GOP senators to vote against advancing the Biden aid package to show they are “serious” in demanding border changes.

“Now is the time to pay attention to our own border in addition to these other important international concerns,” McConnell said.

Republicans in the House remain skeptical of sending more wartime funding to Ukraine.

The White House has declined to discuss publicly the details of the border negotiations and urged lawmakers to pass Biden’s emergency funding request.

“I think that the president has been very, very clear and senior administration officials will be very clear to every single member of the House and Senate today about what the stakes are in Ukraine at this moment,” Olivia Dalton, the White House principal deputy press secretary, said Tuesday on Air Force One while Biden traveled to Boston for campaign fundraisers.