(CNN) The Senate failed Thursday to override President Donald Trump's veto of a bipartisan measure that would have reined in US military support for the Saudi-led war in Yemen that has killed thousands of civilians.

Needing a two-thirds majority to overcome the veto, the measure was defeated on a 53-45 vote, with seven Republicans joining with Democrats.

Despite the loss, critics of the Yemen war vowed to keep fighting to end US involvement, arguing it is immoral to participate in the war that has created a humanitarian crisis

Making rare use of the War Powers Resolution, war critics pushed through the House and Senate a measure that would have forced Trump to get permission from Congress before allowing the military to aid Saudi Arabia in its fight against Iran-backed Houthi rebels in Yemen

The votes were also viewed by many lawmakers as a rebuke of Trump's broader policies towards Saudi Arabia, including his refusal to hold Crown Prince Mohammed bin Salman responsible for the murder of journalist Jamal Khashoggi.

But lawmakers who were against stopping US military involvement argued the US does not have "boots on the ground" and is offering only noncombat technical assistance to Saudi Arabia, an ally.

That the measure reached the point of an override vote -- even with its failure -- underscored a dramatic shift in a short period of time.

Strongly opposed by the Trump administration -- and Republican leadership -- from its inception, the first effort to move it in the Senate failed. A second push in December passed the Senate but was never brought up in the then-Republican-led House. With Democrats in control of that chamber this year, it cleared both chambers in a significant rebuke for the administration.

Its success, at least on Capitol Hill, wasn't driven by a single reason, but a combination of growing outrage, senators and aides made clear.

There was horror from the reports of the civilian suffering in Yemen, outrage related to Saudi Arabia, particularly in the wake of Khashoggi's murder and explicit frustration with an administration that members of both parties said kept them in the dark about both aforementioned issues.

"The murder of Jamal Khashoggi and the tepid response by the White House was the reason the circumstance changed dramatically," Sen. Tim Kaine, a Virginia Democrat, said in an interview. "When the White House demonstrated no real response to this brazen murder in a consulate, the Saudi government was lying to world about it, then they got caught -- I think that was sort of the last straw for Congress."

From the outset, Trump administration officials urged lawmakers not to move forward out of concern it would undercut their negotiating strategy in efforts to reach a peace agreement in Yemen. Secretary of State Mike Pompeo was particularly forceful in telling lawmakers the effort would serve only to empower Iran.

But the administration's push to undercut the resolution, particularly before its Senate passage in December, at times appeared to only bolster its support, and the effort, according to Kaine, did produce results. The US halted refueling of Saudi coalition aircraft engaged in the civil war. It also became clear the US wasn't being reimbursed for the costs of that fueling.

"The effort, even though we're not going to get enough to overturn the President's veto, it has had an effect and that's good," Kaine said.

And it's an effort, despite the Trump's blocking of the measure that its supporters say won't end with the sustained veto.

"Frequent repetition on this one is likely to be our friend," one GOP senator who supported the effort told CNN. "Continuing to run it up the flag pole is probably the only way we'll make progress."

Sen. Chris Murphy, a Connecticut Democrat and key co-sponsor of the effort, said the next steps will be to try and cut funding for the coalition through the appropriations process or through restrictions imposed in the National Defense Authorization Act, and he was "optimistic" something could get done.

Asked if the Trump administration had done anything to assuage concerns over their role in the Saudi campaign, Murphy said simply: "No. And the Saudis are getting even more brazen."

The vote was the first veto override attempt for the GOP-controlled Senate under the Trump administration, and it came on what was only the second veto by Trump.

In his veto message last month, Trump said had the resolution become law, it would have endangered Americans.

"This resolution is an unnecessary, dangerous attempt to weaken my constitutional authorities, endangering the lives of American citizens and brave service members, both today and in the future," Trump said in a message to the Senate.

Trump called the resolution "unnecessary" in part because there are no United States military personnel in Yemen "commanding, participating in, or accompanying military forces of the Saudi-led coalition against the Houthis in hostilities in or affecting Yemen."

The measure had bipartisan support but not enough for an override. Sixteen Republicans voted with Democrats when the measure passed the House and seven Republicans voted with Democrats when it passed the Senate.

But even beyond the Yemen civil war, the push may have a longer -- and more lasting -- impact on how the US approaches hostilities, its supporters say.

The resolution marked the first time a War Powers resolution reached the Senate floor. The way it was done, through expedited procedures and over the opposition of the Senate Majority Leader Mitch McConnell, creates a new pathway for Congress to attempt to restrict an administration's power to enter conflict without any formal authorization -- something that administrations of both parties have either sought to do, or done based on an expansive legal theory, for the last several decades.

"This and any other administration should know that we won't hesitate to do it again if we think they're acting unilaterally to get us into military action or war without congressional support," Kaine said.