(CNN) - Trump administration officials lifted a hold on $250 million in military assistance to Ukraine on Wednesday, multiple sources told CNN, ending weeks of uncertainty about the future of the aid.
The move came as lawmakers prepared to vote on a measure that could have forced the administration to release the funds, which the White House effectively froze when officials initiated a review of Ukrainian defense aid late last month.
Their decision to pause the money sparked bipartisan concern about the potential consequences for Ukraine, as well as the potential benefits for Russia. The assistance included sniper rifles, rocket-propelled grenade launchers, counter-artillery radars, night vision and military medical treatment -- all of which Ukrainians could use to counter pro-Russian separatists.
But under pressure from lawmakers, the White House quietly allowed the funding to move forward this week, in what is just the latest surrender from the Trump administration when it comes to foreign aid. Officials also abandoned an effort in August to cut $4 billion in aid across the board amid a bipartisan backlash.
Military aid to Ukraine is protected in a draft stopgap spending bill, as well as funding for other areas of foreign aid, an administration official said. Secretary of State Mike Pompeo had advocated internally for allowing the funds to move forward, but the Office of Management and Budget pursued the initial hold, according to a source familiar with discussions.
Trump had tapped Secretary of Defense Mark Esper and then-national security adviser John Bolton to oversee the review, a senior administration official told CNN. However, although the Pentagon recommended to the White House in late August that the funding move ahead, the hold remained in place for several weeks. Bolton had been traveling to meet with Ukrainian officials in Kiev at the outset of the suspension, and sources told CNN the review would not be concluded until he returned.
White House officials lifted their hold just two days after Bolton's ouster from the administration. Acting chief of staff Mick Mulvaney was one top voice in favor of blocking the aid to Ukraine.
A senior administration official confirmed Thursday that the State Department and Pentagon would proceed with "the obligation of all military and security assistance funding to Ukraine."
"The administration supports Ukraine's efforts of reform and self-defense, and these funds will advance Ukrainian efforts toward those ends," the official said.
Sen. Dick Durbin of Illinois had proposed an amendment that would have withheld $5 billion from next year's defense budget unless the Trump administration delivered the suspended aid to Ukraine. Several Republican senators -- including Sen. Lindsey Graham of South Carolina and a staunch Trump ally -- had threatened to support the amendment.
Graham credited Durbin's measure with forcing the White House's hand.
"So why was it released? Because of your amendment, that's why it was released," Graham said during an appropriations hearing on Thursday. "Because I was going to vote for it, so I think they got the message. If you're listening in the Ukraine on C-SPAN, you're going to get the money."
Questions remain about whether the Pentagon can actually execute the $250 million in military assistance to Ukraine, however. Congress appropriated that sum for the fiscal year that ends on September 30 -- leaving just a few weeks for the administration to deliver on millions of dollars in aid.
"We expect the majority of the funds to be obligated by the end of the fiscal year. There are measures that would allow us to request an extension from Congress for those funds that remain unobligated," a US defense official told CNN after the White House hold on the assistance was lifted.
Vice President Mike Pence met with Ukrainian President Volodymyr Zelensky in Poland earlier this month, during the suspension of the aid. At the time, Pence blamed the pause in assistance on Trump's "great concerns about issues of corruption."
"I mean, to invest additional taxpayer in Ukraine, the President wants to be assured that those resources are truly making their way to the kind of investments that will contribute to security and stability in Ukraine," Pence said.
Critics had accused the President of slow-walking the aid in order to appease Russia, which annexed the Ukrainian territory of Crimea in 2014.
This story has been updated with additional developments.