WASHINGTON — Top administration officials urged senators Wednesday to keep supporting U.S. involvement in the Saudi-led war in Yemen, but it was unclear whether their message would dissuade lawmakers who want to punish the kingdom for its role in the murder of journalist Jamal Khashoggi.

The Senate was to take a procedural vote later Wednesday on whether to consider a resolution that would end U.S. assistance for the conflict that human rights advocates say is wreaking havoc on the country and subjecting civilians to indiscriminate bombing. After a closed-door briefing with Secretary of State Mike Pompeo and Defense Secretary James Mattis, several senators said they were unsatisfied and likely to back the resolution to halt U.S. support for the war.

The White House issued a veto threat for that resolution, even as Pompeo and Mattis spoke with the senators. Emerging from the briefing, Pompeo said the vote would be "poorly timed" as diplomatic efforts to end the conflict were underway.

Senate Majority Leader Mitch McConnell said Tuesday that "some kind of response" was needed from the United States for the Saudis' role in Khashoggi's gruesome death. While U.S. intelligence officials have concluded the Saudi crown prince, Mohammed bin Salman, must have at least known of the plot, the CIA's findings have not been made public and President Donald Trump has equivocated over who was to blame.

Pompeo said after the briefing that there was "no direct reporting" connecting the crown prince to the murder, and Mattis said there was "no smoking gun" making the connection. In the briefing, Pompeo argued that the war in Yemen would be "a hell of a lot worse" if the United States were not involved.

A similar resolution fell six votes short of passage earlier this year, but some senators apparently were ready to switch. Foreign Relations Committee Chairman Bob Corker, R-Tenn., said he would prefer an appropriate response from the administration, but barring that, "It's very likely I will support getting on it."

Corker said in the past he has "laid in the railroad tracks to keep us from doing things that I believe are against our national interest as it relates to Saudi Arabia." But he said he believes the Senate should "figure out some way for us to send the appropriate message to Saudi Arabia that appropriately displays American values and American national interests."

He said the crown prince "owns this death. He owns it."

McConnell made similar remarks Tuesday, saying that "what obviously happened, as basically certified by the CIA, is completely abhorrent to everything the United States holds dear and stands for in the world."

The unsuccessful March vote on the resolution, sponsored by Republican Sen. Mike Lee of Utah and Independent Sen. Bernie Sanders of Vermont, drew a mix of Democrats and Republicans who had grown uneasy with U.S. involvement in the Saudi-led campaign against Houthi rebels in Yemen.

That number appears to have increased after the Oct. 2 death of Khashoggi, the U.S.-educated journalist who was publicly critical of the Saudi crown prince.

New Jersey Sen. Bob Menendez, the top Democrat on the Foreign Relations panel, said he would switch his vote and support the resolution. Democratic Sens. Chris Coons of Delaware and Jack Reed of Rhode Island also said they were changing their votes, and Sen. Joe Manchin, D-W.V., said he was reconsidering his position.

The resolution needs just a simple majority to advance, but could launch an amendment process that could play out for days in the Senate. While passage of the resolution would be a rebuke to the Saudis and the administration, it would also be a largely symbolic move as House Republican leaders have given no indication they would take up the war powers measure before the end of the year.

Democratic Sen. Chris Murphy of Connecticut, a supporter, said he was more confident about the resolution vote after the briefing. The administration "did not win any votes," he said, and there was a lot of frustration that CIA Director Gina Haspel did not attend.

Menendez speculated that Haspel didn't attend because she "would have said with a high degree of confidence that the crown prince of Saudi Arabia was involved in the murder of Jamal Khashoggi."

Sen. Lindsey Graham, R-S.C., said he would insist on a briefing from Haspel, even threatening to withhold his vote on key measures if that didn't happen. "I'm not going to blow past this," he said.

In a statement, CIA Press Secretary Timothy Barrett said that no one kept Haspel away from the briefing.

He said CIA had already briefed the Senate intelligence committee and Senate leaders and "will continue to provide updates on this important matter to policymakers and Congress."

Mattis, in prepared remarks released before the closed briefing, said that "we must maintain our twin requirements of holding those responsible for the murder to account, while recognizing the reality of Saudi Arabia as a necessary strategic partner."

"We cannot be deflected from using all our influence to end this war for the good of innocent people in trouble, and ultimately the safety of our own people, and this includes our military engagement," Mattis said.

Pompeo said U.S. involvement in the Yemen conflict is central to the Trump administration's broader goal of containing Iranian influence in the Middle East. His language was blunt in a Wall Street Journal article published Tuesday, writing that Khashoggi's murder "has heightened the Capitol Hill caterwauling and media pile-on. But degrading U.S.-Saudi ties would be a grave mistake for the national security of the U.S. and its allies."

Khashoggi was killed in what U.S. officials have described as an elaborate plot at the Saudi consulate in Istanbul, which he had visited for marriage paperwork.

Trump has said it may never be known who was responsible for the killing, and in public comments — and a long and unusual statement last week — he reinforced the United States' long-standing alliance with the Saudis. Trump has praised a pending arms deal with the kingdom that he says will provide the U.S. with jobs and lucrative payments, though some outside assessments say the economic benefits are exaggerated.

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Associated Press writers Lisa Mascaro, Matthew Daly, Kevin Freking, Maria Danilova and Laurie Kellman in Washington contributed to this report.