President Biden was set to denounce Russia's "naked aggression" in Ukraine in a speech on Wednesday to world leaders at the United Nations General Assembly.
With the invasion dragging on, Biden plans to issue an unapologetic condemnation of Russia for violating the principles that the international body stands for.
"He'll offer a firm rebuke of Russia's unjust war in Ukraine and make a call to the world to continue to stand against the naked aggression that we've seen these past several months," White House national security adviser Jake Sullivan said in a preview of the president's speech.
Biden's address to nearly 150 leaders gathered mostly in person for the first time in three years comes as Russian-controlled regions of eastern and southern Ukraine have announced plans to hold Kremlin-backed sham referendums on joining Russia.
With Russian invasion forces losing ground, strongman Vladimir Putin sought to preempt Biden's speech by announcing a partial mobilization to call up 300,000 reservists earlier Wednesday.
Ukraine aside, Biden is confronting no shortage of difficult issues as leaders gather this year.
Europe and the world fear a recession sparked by food and energy price spikes. Time is running out to revive the Iran nuclear issue. And relations with China are strained by outspoken U.S. defense of Taiwan.
Biden also plans to meet with newly minted British Prime Minister Liz Truss as he seeks to bolster the "special relationship" between the two close allies.
The global dynamics have changed dramatically since Biden's speech last year, when he vowed to reengage with the world after former President Donald Trump's mercurial rule.
That speech won widespread praise, but the bar is set much higher this year, with economic and political woes causing global jitters
Biden's visit to the U.N. also comes as his administration's efforts to revive the 2015 Iran nuclear deal appear stalled.
Sullivan said no breakthrough with Iran is expected during the General Assembly but Biden would make clear in his speech that a deal can still be done "if Iran is prepared to be serious."
Biden and first lady Jill Biden were set to host a leaders' reception on Wednesday evening.
Beyond diplomacy, the president is also doing some domestic politicking. With the midterm congressional elections looming, Biden spoke at a Democratic National Committee fundraiser for about 100 participants that raised nearly $2 million Tuesday. He'll hold another fundraiser on Thursday before heading back to Washington.
With News Wire Services