A bipartisan group of six US senators intensified pressure on President Donald Trump on Tuesday to abandon a federal diesel procurement arrangement they say indirectly funds Russia's war in Ukraine. The lawmakers sent a formal letter to the White House and the Department of Energy.

The senators argued that the diesel, refined from Russian-origin crude, undermines Washington's own sanctions regime. They warned that continued purchases would weaken the administration's leverage as tensions with Moscow escalate following renewed Russian strikes on Ukraine's power grid.

The group urged the Energy Department to audit its fuel supply chain and certify that no purchases trace back to sanctioned Russian producers. The demand placed the administration in a difficult position, caught between domestic energy cost concerns and mounting criticism that its Russia policy lacks coherence.

Senate Democrats signaled they would seek a floor vote or hearing if the White House declined to act within a set deadline. A Department of Energy spokesperson acknowledged receipt of the letter but did not commit to changing procurement practices, saying the office was reviewing the senators' concerns and would respond through appropriate channels.