'They're all coming at you at once': How Biden confidants say the president prepared for this moment of war

• The Ukrainian president has called on Biden to be a "leader of the world."
• Republicans say Biden isn't measuring up to the moment.

Before his March 1 State of the Union address, President Joe Biden was talking to his friend "Tommy" – Sen. Tom Carper – about the difference between being a senator and president.

"He says, 'Tommy, the issues are the same,'" Carper, a Democrat who represents Biden's home state of Delaware, told Insider. "He said, 'The difference is, when you're president, they're all coming at you at once.'"

A protracted pandemic and economic problems at home would be enough to challenge and shape any presidency. But Russia's attack on Ukraine that began in February represents another monumental test for the former vice president and senator of 36 years, now as a world leader attempting to halt a battle that some fear could lead to another world war

"Look, he has an extremely – this is the understatement of the century – extremely challenging responsibilities at this time in world history," Sen. Ben Cardin, a Maryland Democrat and Senate Foreign Relations Committee member, told Insider.

Ukrainian President Volodymyr Zelenskyy challenged Biden to "be the leader of the world" during an emotional appeal to Congress Wednesday. Republicans in Congress say Biden is not measuring up to the moment.

"Our own president needs to step up his game," Senate Minority Leader Mitch McConnell, a Republican of Kentucky, told reporters after Zelenskyy's speech. "We're not doing nearly enough, quickly enough, to help the Ukrainians."

Some Senate Republicans say Biden should do more, giving Ukraine access to the fighter jets it wants, despite concerns that it would draw the US further into the conflict.

Biden's allies, however, say the president has already taken decisive action with sanctions against Russia and supplying weapons to Ukraine. On Wednesday, Biden announced the rollout of more weapons systems and financial assistance to Ukraine, a package amounting to about $800 million in security assistance.

"Most importantly, President Biden's been able to do something that's been extremely difficult in recent decades and that is to unify the world – not only our traditional partners – but the global community against the aggression of Mr. Putin and Russia," Cardin said. "But for President Biden, Ukraine would be in a much more difficult position today than they're already in."

Biden served as chairman or ranking member of the Senate Foreign Relations Committee between 1997 and 2009, when he left to become Barack Obama's vice president. He has long prided himself on his personal connections and interactions with leaders around the globe.

"He believes that all politics is personal, he believes that all diplomacy is personal," Carper said. "You can see that in the way he deals whether it's Putin or whether it's Zelinskyy or Mitch McConnell."

The approach is far different from that of former President Donald Trump, who fought with NATO and even called the European Union, along with Russia and China, a "foe" of the US. His first impeachment in 2019 was tied to his temporary withholding of aid to Ukraine for political purposes as the country battled Russian-backed aggression.

Sen. Chris Coons, another Delaware Democrat and key Biden ally, has previously told reporters that when Biden became president, he invested months in visiting Europe, connecting with NATO allies, British and Canadian partners, and meeting with Russian President Vladimir Putin in person in Geneva to convey the message that Biden knows Putin's intentions. Biden has also pledged to "defend every inch of NATO territory."

"Biden has been able to help unify NATO countries in a way that was unthinkable a few years ago, during the last administration," said Josh Schwerin, a Democratic strategist who worked for the pro-Biden group Priorities USA during the 2020 election. "I don't think he would describe himself as the leader of the world. But he is playing a key role in uniting the world behind Ukraine."

Biden is facing pressure to do more, especially after Zelenskky's impassioned plea to Congress that emboldened Republicans to demand what they describe as a tougher response from the White House to the crisis.

Coons, a member of the Senate Foreign Relations Committee, told reporters on Wednesday that he expects Congress to keep pressuring Biden, but that he hopes members will recognize that the effectiveness of sanctions imposed by the West lies in their coordination. The outcome of actions taken so far has been stronger because the administration brought in European partners and allies first, he said.

Zelenskyy makes "an incredibly compelling case" by asking why the world should wait until Putin invades other countries, Coons said.

"It really is just a fundamental question of how much risk are we willing to take, that a cornered authoritarian with one of the world's largest nuclear arsenals, will use it?" Coons said. "It's a relatively simple but very grave conversation. I said to the president yesterday that, in some ways, I think this is the most tense and fraught moment – the riskiest moment – we've had in US-Russian relations since the Cuban Missile Crisis."

Zelenskyy has asked for a no-fly zone over Ukraine, but Biden's allies say they believe Zelenskyy understands the US can't commit to one because it would lead to a broader conflict.

"I think he plays that to get leverage on as many issues as he possibly can," Cardin said.

Carper said he would ask for the "sun, the moon, and the stars," if he were the president of Ukraine because it puts the US in a position to find another solution.

The aid package Biden announced on Wednesday may be more effective "and by the same token, not create a World War III," Carper said.