Ukrainian President Volodymyr Zelensky said Sunday his country's victory "depends" on Western support and that he was "sure" the United States would approve a critical package of military aid.
He also said 31,000 Ukrainian soldiers had been killed in two years of war with Russia, in a rare admission of military losses.
"Whether Ukraine will lose, whether it will be very difficult for us and whether there will be a large number of casualties depends on you, on our partners, on the Western world," Zelensky said.
He spoke at a press conference in Kyiv dedicated to the second anniversary of Russia's invasion at a time when Ukraine has been weakened by a shortage of ammunition and the blocking of US aid in Congress.
"There is hope for Congress, and I am sure that it is going to be positive, otherwise I do not understand the world we will start to live in," Zelensky said.
The aid has been blocked amid resistance from Republicans.
For the first time, Zelensky put a number on Ukraine's military losses in two years of brutal fighting with Russia, saying "31,000 Ukrainian soldiers died in this war."
"Not 300,000 or 150,000, or whatever (Russian President Vladimir) Putin and his lying circle are saying. But each of these losses is a great loss for us," he added.
Both sides are believed to minimise deaths of troops.
Asked if he would talk to Putin, Zelensky said:
"Can you talk to a deaf person? Can you talk to a man who kills his opponents?"
Putin's main opponent Alexei Navalny died in an Arctic prison this month.
"He sees himself (in power) by 2030, we would like to finish with him sooner," Zelensky added, mocking an upcoming presidential election in Russia that is likely to extend Putin's long rule until 2030.
