A bipartisan effort to end US involvement in a bloody, three-year war in Yemen failed in a close Senate vote on Tuesday afternoon.

The vote demonstrated growing pushback on President Donald Trump’s coziness with Riyadh, which is leading the war effort in Yemen. That same day, the president met with Saudi Crown Prince Mohammed Bin Salman, who was visiting Washington during a country-wide tour.

A disparate group of senators — Bernie Sanders (I-VT), Mike Lee (R-UT), and Chris Murphy (D-CT) — drafted and introduced the resolution to stop America’s support for the bloodshed. “This is one of the great humanitarian disasters of our time,” Sanders told Vox in an interview last week.

But the GOP-controlled Senate voted to table — that is, kill — the resolution that says America shouldn’t assist Saudi Arabia in its three-year fight against Iran-backed Houthi rebels in Yemen. By a 55-44 margin, a majority of Republicans and some Democrats effectively said the US can still help Riyadh, by refueling its planes and providing intelligence in the Saudi’s brutal air campaign.

Supporters of the resolution claimed it would immediately end America’s involvement in the war; critics said it wouldn’t.

So far, the conflict has claimed more than 13,500 lives — many of them in airstrikes. Roughly 20 million Yemenis need humanitarian assistance to meet basic needs — including food and water — out of a prewar population of 28 million, and nearly 1 million people are suffering from cholera. However, conditions are so bad there that it is hard to have a reliable tally of any of these measures, which means the situation could be much, much worse.

Part of the reason it’s so hard to navigate Yemen is Riyadh’s relentless bombing campaign. The Saudi military has conducted more than 145,000 missions in Yemen over the past three years. A Saudi general told the Wall Street Journal that about 100,000 of those were combat missions, conducting about 300 missions per day. One human rights group counted around 16,000 Saudi airstrikes in total, killing thousands of civilians in total.

During a blockade last year, Saudi Arabia put various restrictions on Yemen’s airspace and seaports, which led to the deaths of more than 5,000 civilians, more than 20 percent of whom were children.

Lee, one of the measure’s co-sponsors, told me the push to pass the resolution was also to make a statement about how America goes to war. “We have a set of processes that have to be followed,” he said, noting that Congress has the constitutional authority to declare war. “If advocates for this war within our government are confident that this is that important to America’s national security interest, then they should bring forward those arguments and ask for an authorization,” he continued. “But without that, we have no business getting involved in someone else’s civil war.”

The Trump administration lobbied to defeat the measure. Last week, Secretary of Defense Jim Mattis sent a letter to Congress requesting that lawmakers not restrict America’s support for Riyadh’s military. He claimed that stopping US assistance “could increase civilian casualties, jeopardize cooperation with our partners on counterterrorism, and reduce our influence with the Saudis — all of which would further exacerbate the situation and humanitarian crisis.” Mattis traveled to the Hill on Tuesday to encourage members of both parties to block the resolution.

This isn’t the first time Congress has tried to stand up to the president on America’s involvement in Yemen. Last November, the House of Representatives passed a similar resolution to the Senate version. That’s because, by a wide 366-30 margin, the House believed the US is only authorized to fight terrorist groups like ISIS or al-Qaeda. Lawmakers said the US doesn’t have authorization to fight the Houthis.

Rep. Ro Khanna (D-CA), who led the House effort, noted his displeasure with the vote in an interview with me but struck a note of optimism. “Eventually, we will prevail because our position is on the side of human decency and human rights, consistent with basic American values,” he told me. “We just need to keeping speaking up for peace and for the children in Yemen.”

Scott Paul, a Yemen expert at the humanitarian group Oxfam America, was unhappy with the news, telling me that “today should have been the day that the Senate moved to end US involvement in this catastrophe.” But Paul noted that some senators may have voted against the measure because the Senate Foreign Relations Committee may soon take up the issue. “We expect Congress to take decisive action soon,” he said.

But Tuesday’s vote was relatively close, and that is important on its own. It’s even more noteworthy because on Tuesday, Trump welcomed Saudi Arabia’s crown prince and the driving force behind the Yemen war to the White House to discuss their burgeoning relationship and arms sales.

Trump had previously issued statements asking Saudi Arabia to cease violating human rights in Yemen. But in his two public statements alongside MBS, as the crown prince is widely known, at the White House, Trump didn’t mention the word “Yemen” once.

One man drives the Saudi-led war on Yemen

Mohammed bin Salman, Saudi Arabia’s de facto leader, champions the fighting in Yemen. It’s part of his aggressive anti-Iran policy in the Middle East, which led him to intervene in Yemen in support of the internationally recognized government against the Houthis.

Iran’s government is a Shia Muslim theocracy; Saudi Arabia’s government is a monarchy closely aligned with the country’s Sunni Muslim religious establishment. The two countries represent two ideological and political poles and have spent decades fighting each other for dominance in the Middle East and for the right to represent the Muslim world.

MBS, along with his father, King Salman, completed a purge of an astonishing 11 princes and dozens of other officials and businessmen last November. That allowed MBS to consolidate even more power in Saudi Arabia, which gives him even more authority to direct Riyadh’s war in Yemen.

Trump continues to support MBS, going so far as to approve his purge in a tweet on November 6. At a joint appearance at the White House on Tuesday, Trump continued to show his backing for MBS and Saudi Arabia writ large.

“The relationship is probably the strongest it’s ever been,” Trump said. “We understand each other.”

Zack Beauchamp contributed to this report.