The US Senate has failed to approve an emergency budget bill that includes aid for Ukraine.

A bipartisan group of senators put together a package including security measures for the border with Mexico and wartime aid to Ukraine and Israel. But most Republicans voted against advancing it in the chamber on Wednesday after former President Donald Trump, who is seeking re-election in the presidential race this year, urged them not to compromise.

The United States has been Ukraine's biggest backer, but funding ran out at the end of last year. Congress has failed to pass an additional budget bill that includes fresh military aid for Ukraine due to differences between the Democrats and Republicans.

Republicans hold a majority in the US House of Representatives. House Speaker Mike Johnson, who is close to Trump, has called for stricter border controls and has been reluctant to support Ukraine.

Aid for Ukraine and border security are key issues in the upcoming presidential election. It is becoming increasingly unclear whether the US will continue to support Ukraine in the nearly two-year old conflict.