The death of Sen. Lindsey Graham (R-South Carolina) comes as Kyiv is set to lose many Republican allies in Congress.

Sen. Lindsey Graham stood in front of captured Russian military equipment in Kyiv on Friday and announced a breakthrough.

After more than a year of excruciating negotiations with the White House, the South Carolina Republican had reached an agreement to advance a bipartisan bill that would clamp down on Russian President Vladimir Putin’s wartime economy.

“We have the best chance since I’ve been coming here in the last five years to get Putin to the peace table,” Graham said at a news conference.

Graham’s death this weekend after what a preliminary medical report said was an “aortic dissection” has cast uncertainty over the moment of triumph for Ukraine and its allies in Congress. In the senator, Kyiv has lost a chief Republican backer who served as an envoy to President Donald Trump.

“I can’t imagine who can take his place,” Oleksandr Merezhko, head of the foreign relations committee in Ukraine’s parliament, said in an interview.

Many other Republican supporters of Ukraine are set to leave Congress early next year in a trend that could present lasting challenges for the government in Kyiv. Growing factions of the Republican Party have grown increasingly skeptical of U.S. support for Ukraine and other foreign allies.

Even as Washington has signaled increased support for Ukraine in recent weeks, officials in Kyiv were concerned about their future standing without a key Trump whisperer.

On Sunday, lawmakers supportive of Ukraine urged Congress to quickly take up the bipartisan sanctions package, which would seek to punish countries for purchasing Russian oil in an attempt to force the Kremlin to end the full-scale invasion of Ukraine.

“It is his bill, and the best thing Congress could do to honor his legacy would be to pass that bill,” Rep. Michael McCaul (R-Texas), the former chair of the House Foreign Affairs Committee, said in an interview.

McCaul visited Ukraine this week to meet with President Volodymyr Zelensky, arriving only hours after Graham had also met with the president on his latest trip to the country. The two lawmakers didn’t see each other on the trip but planned to introduce the sanctions bill together this week, McCaul said.

Multiple lawmakers and congressional aides projected confidence that the package would receive quick consideration out of respect for the senator.

Sen. Richard Blumenthal (Connecticut), Graham’s main Democratic counterpart on the effort, said that Senate leaders had committed to holding a vote on the bill when it had enough support to pass — and that now it did.

“This time feels monumentally different because we have White House support,” Blumenthal said in an interview Sunday.

Some aides involved in the effort cautioned that it was unclear whether the bill would reach the floor before lawmakers again leave Washington for the month of August.

“It was Graham’s baby,” a GOP aide said on the condition of anonymity because they were not authorized to speak with the press. “No one is going to push it like he did.”

Still, in an interview before the senator’s death, Rep. Joe Wilson (R-South Carolina), argued that support for Ukraine was as strong as ever in the House, rejecting the “isolationists” in his party calling for Washington to pull back from its military commitments abroad.

Last month, Wilson supported a separate bill that would tighten sanctions on Russia and provide Ukraine with more than $8 billion in security assistance.

But while the legislation received bipartisan support, it only reached the House floor after several Republicans broke with the chamber’s leadership to force a vote. Even after it did, only 18 GOP lawmakers supported it — a far smaller number than the majorities that approved almost $200 billion in security and humanitarian assistance for Ukraine following Russia’s 2022 invasion.

The bill passed the House but has yet to receive a vote in the Senate.

In the longer term, supporters of Ukraine in Congress said that they were concerned about the number of allied lawmakers who were departing.

Sen. Thom Tillis (North Carolina) and Rep. Don Bacon (Nebraska), two staunch GOP Russia hawks, are retiring at the end of their terms this year. Sen. Mitch McConnell (Kentucky), the Republican chair of a panel on defense spending, has been hospitalized for several weeks and is also retiring.

“I don’t think he’s the only guy, but others will have to speak up more,” Bacon said of Graham in an interview Sunday.

Despite his overall support for Ukraine, Graham has at times experienced tension with its government.

Last February, Ukrainian officials felt betrayed by Graham’s pro-Trump response to Zelensky’s disastrous meeting in the Oval Office, which ended in Trump berating Zelensky and expelling him from the White House.

Graham and Zelensky later repaired their relationship, and the senator kept visiting Ukraine. Following Graham’s death, Ukrainian officials worried that the senator’s political canniness and personal relationship with Trump would be hard to replace.

“He really was one of the people speaking Trump’s language,” said Olga Stefanishyna, Ukraine’s ambassador to Washington, in an interview.

Last week, Trump and Zelensky praised each other during a meeting on the sidelines of the NATO summit in Ankara, Turkey. Trump later agreed to eventually allow Ukraine to build advanced Patriot air-defense interceptors, one of Kyiv’s longtime priorities.

McCaul framed Graham as a central figure in lobbying the president to remain in the NATO alliance — despite Trump’s complaints that European allies needed to spend more on defense — and to continue U.S. assistance for Ukraine. He said that Graham had advocated for the Patriot deal, one of many priorities the senator promoted when he got face time with Trump.

“I don’t think Lindsey was that great of a golfer,” McCaul said. “But he played golf because he could get the president’s ear for nine or 18 holes.”