Ahead of Wednesday's summit in Switzerland, both leaders agreed that it is a "low point" between the U.S. and Russia relationship

Ahead of the summit, ABC News Chief Global Affairs Correspondent Martha Raddatz said Biden needs to walk a fine line in an effort not to alienate Putin.

"He wants the relationship to be better — the U.S.-Russia relationship — to be better than it has been," Raddatz said on ABC News Live Prime Tuesday. "And they both agree that it's at one of the lowest points in history."

"So, President Biden will have to give his grievances to Putin, telling him what he wants to do — and yet, we even heard a bit of that today, a little flattery, a little, you know, he is a 'tough guy,' he is a 'bright guy,' President Putin, and he is a 'worthy adversary,'" Raddatz continued. "That is diplomacy 101."

In a separate interview with ABC News' Linsey Davis, Masha Gessen, a staff writer at the New Yorker and author of "Surviving Autocracy," agreed that "Russian-American relations are at an all time low."

"Biden is faced with an incredibly difficult challenge," Gessen added.

Watch the interview:

Amid all the high-level shadow boxing setting up President Joe Biden's summit with Russian President Vladimir Putin, Biden has added a new wrinkle -- one that amounts to a test for himself that awaits him back home.

Biden has cast this moment in the world community in broad terms for the United States -- a chance to assert the power of democratic nations in the face of challenges from China and Russia in particular. Asked Monday what he is telling allies who may be worried about any American slide toward autocracy, Biden again went big.

"What I'm saying to them is, watch me," Biden said. "That's why it's so important that I succeed in my agenda."

Biden was nonchalant in his condemnation of what he called the "phony populism" of former President Donald Trump. Speaking about Republicans, he flatly observed that "the Trump wing of the party is the bulk of the party, but it makes up a significant minority of the American people."

Still, just hours earlier, Senate Minority Leader Mitch McConnell served notice that his brand of hardball is still going to be played, with a warning about what Republican Senate control would mean for any Supreme Court vacancy under a Democratic presidency.

McConnell is objecting to congressional scrutiny of Trump-era Justice Department strategies, just like he did to the proposed Jan. 6 commission. And it's still far from clear whether any infrastructure or climate-change legislation can pass with Republican support, to say nothing of the prospects for tax reform.

Asked about Putin's laughing response to Biden's assertion that he is a killer, Biden said his message back would be that he is laughing as well. The world now is watching -- and will still be when Biden and Putin are both back home.

-ABC News Political Director Rick Klein

Biden met with Swiss President Guy Parmelin and Foreign Minister Ignzio Cassis Tuesday and, according to a White House readout, Biden thanked the country for hosting the U.S. -Russia summit and "expressed appreciation for Switzerland's unique historical role providing a neutral ground for diplomacy and negotiations."

Biden and the leaders also talked about the strong relationships between the U.S. and Switzerland on many fronts. They also discussed Switzerland's role as the U.S. protecting power in Iran for 40 years and their contributions to the global COVID response effort.

-ABC News' Molly Nagle

When Putin meets Biden on Wednesday in Switzerland, experts in Moscow say for all their differences, the two leaders want something similar from their first summit: to cool things down.

The U.S. and Russia's relations are the worst they have been since the Cold War and since 2016 in particular seem locked in almost permanent crises.

Biden has said he wants a more stable and predictable relationship with Russia, one that would allow it to focus on other foreign policy priorities that are more important to it, like taking a harder line with China. The Kremlin for its part has faced a continuous and intensifying barrage of sanctions-- the latest in April-- and with its crackdown on opposition at home and aggressive actions abroad is increasingly becoming a pariah with western countries.

Since coming to office, Russia has appeared to want to get Biden's attention. The president offered Putin the summit after Russia massed thousands of troops on Ukraine's border in April.

But now, having got Biden to the table, analysts said Putin has a clear proposal to deliver in Geneva: stay out of Russian domestic politics and Russia might act less troublesome abroad.

"The Kremlin wants to transition to a respectful adversarial relationship from a disrespectful one we have today," said Vladimir Frolov, a former diplomat at Russia's embassy in Washington and now a commentator on foreign affairs.

"That is, it wants to be treated the same way the Soviet Politburo was treated by the US in 1970-80s," Frolov told ABC News. "Meaning no name-calling" — such as Biden calling Putin a "killer" — "no personal sanctions on the leadership, no democracy lectures, regular personal summit meetings; respectful tone of discussions, no tangible support for Russian opposition."

It will not be an invitation for détente but instead to return to the later years of the Cold War when Putin was a KGB agent and the Soviet Union and the U.S. saw each other as enemies but tried to maintain a predictable relationship. And, crucially, where Russia was treated as an equal.

"For this, the Kremlin is prepared to promise to behave more responsibly," Frolov said.

"This seems to be in line with what the White House sees as a desirable deliverable," he continued. "So unless one of the leaders stormed out of the meeting shouting expletives, the summit would be a major success."

-ABC News' Patrick Reevell