President Joe Biden slammed Republicans on Monday for not approving more aid for Ukraine and said he hoped the death of Russian opposition leader Alexei Navalny would spur them into action.

The Senate passed a $95 billion aid package that includes funds for Ukraine, but House Speaker Mike Johnson is refusing to bring it up for a vote and is demanding a meeting with Biden. 

'Sure I'd be happy to meet with him, if he has anything to say,' the president said as he returned to the White House after a weekend in Delaware. 

The issue has taken on added intensity in recent days after one of President Vladimir Putin's leading critics died in a Russian prison.

Biden was asked by reporters whether Republicans had blood on their hands if they did not pass the bill.

'I wouldn't use that term, but they're making a big mistake by not responding,' he said. 

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

'I've never seen anything like it.'

Former President Donald Trump last week triggered outrage and alarm among US allies by suggesting he would not be willing to defend NATO members who did not meet spending commitments. He even suggested he would encourage attacks on them.

On Monday, Trump finally responded to the death of Navalny, but only to compare himself with the courageous Russian dissident.

'The sudden death of Alexei Navalny has made me more and more aware of what is happening in our country,' Trump posted on his Truth Social platform.

'It is a slow, steady progression, with crooked, radical left politicians, prosecutors, and judges leading us down a path to destruction.'

Biden also said he was considering imposing fresh sanctions on Russia for Navalny's death.

'We already have sanctions, but we are considering additional sanctions, yes,' he said. 

Republicans broadly argue that the war in Ukraine is unwinnable. So why send more money?

Ahead of the Senate vote last week, Republican Sen. Ron Johnson described Putin as 'evil,' before concluding: 'Vladimir Putin will not lose this war.'

In the meantime, Ukraine continues to appeal for more help.

Its forces were forced to retreat from the captured town of Avdiivka, a strategic hub in the east of the country.

The White House said that was due to a lack of ammunition, which it blamed on the congressional logjam.

'This morning, Ukraine’s military was forced to withdraw from Avdiivka after Ukrainian soldiers had to ration ammunition due to dwindling supplies as a result of congressional inaction, resulting in Russia’s first notable gains in months,' it said after Biden called Ukraine's Volodomyr Zelensky.