US President Joe Biden is "considering additional sanctions" on Moscow after the death of Russian opposition leader Alexei Navalny in an Arctic prison, he said Monday.

       "We already have sanctions, but we are considering additional sanctions, yes," Biden, who has already directly blamed Russian President Vladimir Putin and his "thugs" for Navalny's death last week, told journalists in Washington.

       Biden and other Western allies have already used unprecedented sanctions as a way of throttling support for Moscow's war in Ukraine, though so far they have failed to halt the assault.

       But doubts have been growing recently over Washington's future commitment to Ukraine. With existing US funding already dried up, former president Donald Trump's allies in the House of Representatives have been stalling $60 billion in new military aid.

       Trump, the likely Republican nominee in the November presidential election, opposes helping Kyiv and recently used his sway to kill a US border reform bill that would have also authorized additional aid to Ukraine.

       Biden slammed Republicans again Monday over the failure to pass the aid package.

       "The way they're walking away from the threat of Russia, the way they're walking away from NATO, the way they're walking away from meeting our obligations, it's just shocking," he said.

       But he said he would be happy to meet with Mike Johnson, Speaker of the Republican-led House of Representatives, who has told reporters he has no intention of even allowing a vote on the package.

       "Sure, I'd be happy to meet with him, if he has anything to say," Biden said.

       He added that he hoped that Navalny's death would make a difference when it came to passing the aid, but "I'm not sure."