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President Biden on Monday wouldn't divulge any more details about his upcoming summit with Russian President Vladimir Putin, telling reporters he'll discuss the topics of conversation "when it's over."

Biden and Putin will meet Wednesday in Switzerland. He fielded questions from reporters following a meeting with NATO leaders in Brussels, and avoided answering what he expects Putin will say to him or any concessions he might make. Biden did say he has spoken with other NATO leaders who "thanked me for meeting with Putin now. They thought it was thoroughly appropriate that I do so."

While Biden is keeping mum publicly, he asked several leaders during the recent G7 summit in the United Kingdom — including German Chancellor Angela Merkel — for their advice ahead of the Putin meeting, people familiar with the matter told CNN. Biden has also been spending time every day preparing for it with Secretary of State Antony Blinken and National Security Adviser Jake Sullivan, and they have discussed Biden bringing up with Putin everything from cyberattacks to the situations in Syria and Ukraine.

U.S. officials told CNN they are still working out with their Russian counterparts whether there will be a one-on-one meeting between Biden and Putin during the summit, without any notetakers present; as of now, they will have two separate meetings. There won't be a joint press conference at the conclusion of the summit, and Biden will speak to reporters on his own. Officials told CNN Russia requested a joint appearance before the press, but the U.S. does not want Putin to have the chance to appear like he'd gotten the better of an American president. On Sunday, Biden said this is "not a contest about who can do better in front of a press conference or try to embarrass each other."