The high-stakes meeting between Biden and Putin comes on the heels of a summit with NATO leaders in Belgium's capital, another first for Biden as U.S. president.

"What I'll convey to President Putin is that I'm not looking for conflict with Russia but that we will respond if Russia continues its harmful activities," Biden said at a press conference in Brussels. "And we will not fail to defend the trans-Atlantic alliance or stand up for democratic values."

Biden said not a single NATO leader expressed reservations about him meeting with Putin but rather have "thanked" him for doing it.

"I had discussions with them about -- in the open -- about what they thought was important from their perspective and what they thought was not important," he said.

Biden and Putin's meeting is slated to begin on Wednesday around 7 a.m. ET and last four to five hours total, with multiple sessions.

The two leaders will first take part in a small session, joined by U.S. Secretary of State Antony Blinken and Russian Foreign Minister Sergey Lavrov, before taking part in a larger working session.

The two leaders are also expected to host dueling, solo press conferences following the summit.

Biden said they weren't holding a joint news conference, as Trump did with Putin, because he didn't want the focus to be on talking time or body language. Doing it this way leaves Putin with less of an opportunity to embarrass the American president, as he's historically tried to do.

"I think the best way to deal with this is for he and I to meet, he and I to have our discussion," Biden said Sunday in England, on another leg of his first trip as president. "I don't want to get into being diverted by, did they shake hands, who talked the most and the rest."

While he is no stranger to Putin, Biden has been intensely prepping for the meeting, receiving at least once-a-day briefings for weeks leading up to the summit.

"He's been preparing for this like he prepares for every significant international engagement. He reviews the issues -- written material; he cares about digging into the details. That very much matters to him," a senior administration official said Tuesday.

The White House has also called on experts to help Biden prep for the meeting -- including Fiona Hill, a top Russia expert and National Security and former Trump administration official who famously said she considered faking a medical emergency to end Trump’s press conference with Putin in 2018 in Helsinki, Finland.

Wednesday's meeting is slated to last four to five hours total, with multiple sessions.

-ABC News' Molly Nagle

Biden arrived in Geneva earlier Tuesday less than 24 hours ahead of his meeting with Putin, scheduled for Wednesday around 7 a.m. ET and expected to last several hours.

Looking to project confidence ahead of the high-stakes summit, Biden didn’t miss a beat during a photo op Tuesday with Swiss President Guy Parmelin.

"Mr. President, are you ready for tomorrow?" a reporter asked.

"I’m always ready," Biden replied.

The meeting with the Swiss president was Biden's final public event for the day.

When the president arrived earlier in Geneva, he was met with a long line of greeters, many dressed in colorful outfits, as he stepped off Air Force One.

The White House said Biden will hold a solo press conference after meeting with Putin, where he will give his takeaways. Putin plans to do the same.

One critical message the president will carry, according to U.S. Secretary of State Antony Blinken, is demanding that Russia stop "harboring in any way criminal organizations engaged in cyberattacks, including ransomware" and urging "Russian cooperation in dealing with these criminal organizations to the extent they're operating from Russian territory."

But tough talk and mounting U.S. sanctions have not deterred Russian behavior, from crackdowns against domestic political opposition and pro-democracy movements to aggression overseas against neighbors Ukraine and Georgia or western democracies and their elections.

Pressed on that Sunday by ABC "This Week" co-anchor Martha Raddatz, Blinken said U.S. sanctions "can be" effective, "especially when they're done in coordination with other countries."

To that end, he emphasized what the administration had said was the importance of Biden meeting American allies in the Group of Seven, NATO and the European Union before sitting down with Putin.

But some of those alliances are bruised after four years of former President Donald Trump's badgering and questioning -- with many Europeans in particular unsure whether "Trumpism" is here to stay or whether "America is back," as Biden has made his tagline for this trip.

Blinken didn't take that political question head on, but he said the U.S. and its allied democracies have "to actually demonstrate in concrete ways that democracies working together are making a difference for their people and for people around the world" -- especially in contrast to Russia and China.

-ABC News' Conor Finnegan