Ukrainian president had been expected to join Zoom call but ‘something came up at the last minute’

Several Republican senators walked out of a classified briefing on Ukraine Tuesday as it descended into a row over the border crisis, after the Ukrainian president, Volodymyr Zelenskiy, unexpectedly canceled a video-link appearance to appeal for continued US funding.

Zelenskiy had been due to update the senators on the latest developments in the conflict with Russia and press for them to support a procedural vote expected Wednesday on an emergency aid package that includes more than $60bn for Kyiv.

The cash has been held up for weeks in Congress, as the White House has warned that existing funds will run out by the end of the year and that Russia’s president, Vladimir Putin, could win the war if lawmakers fail to act.