Updated 10.08pm
President Joe Biden warned Tuesday that ending US military aid for Ukraine would be a "Christmas gift" for Russia, as Ukrainian President Volodymyr Zelensky's last-ditch bid for more help ran into stiff Republican opposition.
As Moscow claimed fresh battlefield advances and predicted any fresh assistance for Kyiv would be a "fiasco", Zelensky told Biden as they met at the White House that "Ukraine can win".
Zelensky, 45, who wore a black sweater with a small Ukrainian trident symbol, and olive green military trousers, shook hands with the 81-year-old US leader as they sat in front of a roaring fire in the Oval Office.
"We are going to stand at your side," Biden told Zelensky, even though the Ukrainian leader's desperate pleas to Congress to pass $60 billion in new assistance for aid for Kyiv fell on deaf ears.
"Congress needs to pass supplemental funding for Ukraine... before they give (Russian President Vladimir) Putin the greatest Christmas gift they can possibly give him," Biden added.
But Zelensky's attempt to keep Ukraine's main backer onside, after White House warnings that funding for Kyiv will dry up by the end of the year, crashed into the realities of a bitter US domestic political divide.
Republican House Speaker Mike Johnson, the gatekeeper for any deal, said his party would not approve Biden's request for more aid for Kyiv unless Democrats meet their demands on immigration and the US-Mexico border.
"What the Biden administration seems to be asking for is billions of additional dollars with no appropriate oversight, no clear strategy to win, and none of the answers that I think the American people are owed," Johnson told reporters after meeting Zelensky.
- 'Fiasco' -
The Kremlin scoffed at the impact of US support, echoing the arguments made by some senior Republicans who say that continuing the flood of weaponry to Ukraine would be futile after Kyiv's summer counteroffensive stalled.
"It is important for everyone to understand: the tens of billions of dollars pumped into Ukraine did not help it gain success on the battlefield," Kremlin spokesman Dmitry Peskov said Tuesday.
"The tens of billions of dollars that Ukraine wants to be pumped with are also headed for the same fiasco."
Russia said it was pressing ahead on the ground, just as Ukraine's freezing winter deepens and Moscow's air attacks on Ukraine's cities increase.
"Our units have advanced significantly forward northeast of Novopokrovka," said the Moscow-installed head of the Russian-occupied Zaporizhzhia region, Yevgeny Balitsky.
Ukraine said Russia had launched a "massive offensive" with armored vehicles in another part of the front near Avdiivka in the east.
In a blow felt by civilians behind the frontlines, Ukraine's main mobile operator said it had been paralyzed by a "powerful hacker attack."
- 'Deadlock' -
The United States said that in reality, Russia is paying a very heavy price for small gains, with some 315,000 Russian troops killed or wounded in Ukraine since the war began in February 2022.
Russian forces have also lost some 2,200 of the 3,500 tanks they had before the start of the conflict, according to a declassified US intelligence assessment shared with Congress.
The White House said Russia had suffered more than 13,000 dead and wounded in the east just since October.
But "Russia seems to believe that a military deadlock through the winter will drain Western support for Ukraine and ultimately give Russia the advantage despite Russian losses," National Security Council spokeswoman Adrienne Watson said.
As the United States ponders its future Ukraine policy, Kyiv's main European ally Poland urged global support.
Polish prime minister-designate Donald Tusk called for the "full mobilization on the part of the free world, the West in support of Ukraine in this war."
The message will likely be echoed loudly by Biden at the White House.
Republican senators last week blocked Biden's request for $106 billion in emergency aid primarily for Ukraine and Israel.
Talks are ongoing behind the scenes on a deal that would make concessions to Republican demands for tough measures against illegal immigration in return for the Ukraine package.