Opposition from hardline Republicans led lawmakers to exclude new Ukraine funding from a bill passed over the weekend to avert a government shutdown, putting US assistance for Kyiv in doubt.

"We have enough funding authorities to meet Ukraine's battlefield needs for just a little bit longer, but we need Congress to act to ensure there is no disruption in our support," Deputy Pentagon Press Secretary Sabrina Singh told journalists, declining to provide a more specific timeline.

"We do feel confident that we will have bipartisan support to continue to support Ukraine for as long as it takes," Singh said, noting that it "is just a small minority of folks in the House that are expressing their opposition."

She said the government still has authority to withdraw $5.4 billion in equipment for Ukraine from US military stocks, but only $1.6 billion in funding to replace the donated gear.

"That is something that we are urging Congress to look at of course, because we do need to replenish our stocks as we continue to flow aid to Ukraine," Singh said.

US officials have spearheaded the push for international support for Ukraine, quickly forging a coalition to back Kyiv after Russia invaded last year and coordinating aid from dozens of countries.

Washington has committed more than $43 billion in military assistance to Kyiv since Moscow launched its full-scale invasion in February 2022.