On Wednesday, the White House approved an additional installment of US military assistance to Ukraine, totaling approximately $250 million (£195 million). According to US officials, this latest aid package encompasses air defense systems, artillery, small arms ammunition, and anti-tank weaponry. Notably, this marks the final allocation of funds available without a renewed endorsement from Congress, where discussions have hit an impasse.

Ukraine has issued warnings, expressing concerns that both its war effort and public finances are jeopardized if further support from Western allies is not forthcoming. As the country faces a stalemate in the eastern counter-offensive and a relatively unchanged line of control, Ukrainian officials confront the potential deceleration of aid from Washington and European partners.

Despite widespread support for Ukraine's war effort in the US Congress, agreement on additional arms assistance has been hindered by Republicans.

They insist that any military aid deal must include more stringent security measures along the US-Mexico border. An emergency spending proposal, aiming to allocate $50 billion for Ukraine and $14 billion for Israel, was defeated in the Senate earlier this month.

The vote against it included every Republican, along with Bernie Sanders, an independent typically aligned with Democrats but expressing reservations about Israel's conflict with Hamas.

In response to the funding challenges, the Ukrainian President's visit to the United States failed to sway lawmakers. The aid package announced on Wednesday involves withdrawing weapons from existing Pentagon stocks, a measure not requiring Congressional approval.

Secretary of State Anthony Blinken emphasized the urgency of Congress taking swift action to advance national security interests by aiding Ukraine in its defense efforts.

"Our assistance has been critical to supporting our Ukrainian partners as they defend their country and their freedom against Russia's aggression," he added.

Earlier this month a €50bn ($55bn; £43bn) EU aid package for Ukraine was blocked by Hungary.

Ukraine is facing a $43bn (£33.6bn) budget deficit, and officials say they may have to delay salaries and pensions for government employees if further military aid from the West does not come soon.

"The support of partners is extremely critical," Ukraine's Deputy Prime Minister Yulia Svyrydenko, who also serves as the country's economic minister, said in an interview with the Financial Times on Wednesday. "We need it urgently."

The newspaper reported that talks are progressing on a smaller aid package that would not need Hungary's approval, which could be taken up in early February.

As funding has slowed from Ukraine's Western allies, Russian forces have continued to fight in the east of the country, where they seized a key town on Tuesday.

Russian Defence Minister Sergei Shoigu said his troops took the key town of Mariinka in eastern Ukraine after Ukrainian forces pulled back. The town has been at the forefront of fighting for over a year.