President Joe Biden asked Congress on Thursday for an additional $33 billion to help Ukraine fend off Russia's invasion, a signal that the U.S. is prepared to mount a robust, long-term campaign to bolster Kyiv and weaken Moscow as the bloody war enters its third month with no sign of abating.

Biden’s latest proposal - which the White House said was expected to support Ukraine's needs for five months - has more than $20 billion in military assistance for Kyiv and for shoring up defenses in nearby countries. There is also $8.5 billion in economic aid to help keep Ukrainian President Volodymyr Zelenskyy’s government functioning and $3 billion for food and humanitarian programs to help civilians, including the more than five million refugees created by the war.

The assistance package, which now heads to Congress for consideration, would be more than twice as large as an initial $13.6 billion of defense and economic aid for Ukraine and Western allies that Congress enacted last month and is now almost exhausted. It was meant to signify that the U.S. is not tiring of helping to stave off Russian President Vladimir Putin's attempt to expand his nation's control of its neighbor, and perhaps beyond.

“The cost of this fight is not cheap, but caving to aggression is going to be more costly," Biden said. “It’s critical this funding gets approved and as quickly as possible.”

The request comes with the fighting, now in its ninth week, sharpening in eastern and southern parts of the country and international tensions growing as Russia cuts off gas supplies to two NATO allies, Poland and Bulgaria.

There is wide, bipartisan support in Congress for giving Ukraine all the assistance it needs to fight the Russians, and its eventual approval seems certain. But Biden and congressional Democrats also want lawmakers to approve billions more to battle the pandemic, and that along with a Republican push to entangle the measure with an extension of some Trump-era immigration restrictions leaves the proposal's pathway to enactment unclear.

In an accompanying letter to House Speaker Nancy Pelosi, D-Calif., Biden also asked lawmakers to include an additional $22.5 billion for vaccines, treatments, testing and aid to other countries in continuing efforts to contain COVID-19.

But that figure, which Biden also requested last month, seems aspirational at best. In a compromise with Republicans, Senate Democrats have already agreed to pare that figure to $10 billion, and reviving the higher amount would be at best an uphill fight.

As if acknowledging the political problems the pandemic response is encountering, Biden's letter to Pelosi said, “I urge the Congress to include this much needed” pandemic spending in the Ukraine package. That wording seemed to suggest that separating the two initiatives, if needed to speed the Ukraine money, might be palatable to the White House.

Biden was also asking Congress on Thursday for new powers to seize and repurpose the assets of Russian oligarchs.

He wants lawmakers to make it a criminal offense for a person to “knowingly or intentionally possess proceeds directly obtained from corrupt dealings with the Russian government,” double the statute of limitations for foreign money laundering offenses to 10 years, and expand the definition of “racketeering” under U.S. law to include efforts to evade sanctions.

Biden will also ask Congress to allow the federal government use the proceeds from selling the seized assets of sanctioned Russian oligarchs to help the people of Ukraine.

In a virtual address to International Monetary Fund and World Bank leaders last week, Ukrainian President Volodymyr Zelenskyy called for the proceeds of sanctioned property and Central Bank reserves to be used to compensate Ukraine for its losses.

He said that frozen Russian assets “have to be used to rebuild Ukraine after the war as well as to pay for the losses caused to other nations.’’

Treasury Secretary Janet Yellen said at the time that congressional action would be needed to authorize such actions.

The war has already caused more than $60 billion in damage to buildings and infrastructure, World Bank President David Malpass said last week. And the IMF in its latest world economic outlook forecast that Ukraine’s economy will shrink by 35% this year and next.

In recent weeks, the U.S. and global allies have sanctioned dozens of oligarchs and their family members, along with hundreds of Russian officials involved in or deemed to be supporting its invasion of Ukraine. The White House says the new tools will toughen the impact of the sanctions on Russia's economy and its ruling class by making sanctions more difficult to evade.

Biden last week warned that $6.5 billion earmarked for security assistance for Ukraine could soon be “exhausted” and that Congress would need to approve supplemental funding. More than half of the approved money for weapons and equipment for Ukraine’s military has already been drawn down.