10:35 AM PT -- Michael Douglas is seconding the motion put forward by George Clooney ... he was on "The View" Wednesday when he said George is making a "valid point."

MD added, he's "deeply, deeply concerned" -- not so much about "today or tomorrow, but a year down the line ... I worry." He also called out Biden's team for not preparing him better for the debate.

Worth noting, during the convo, Whoopi Goldberg makes it clear she's still riding with Biden ... for now.

George Clooney says President Biden absolutely cannot win the election against Donald Trump, and he's asking him to drop out of the race immediately.

George makes the point he spent a lot of time with Biden just last month, during a Democratic fundraiser in L.A., and says ... "The Joe Biden I was with three weeks ago at the fund-raiser was not the Joe 'big F-ing deal' Biden of 2010. He wasn't even the Joe Biden of 2020. He was the same man we all witnessed at the debate."

Clooney addresses all Democrats in his NYT op-ed letter, saying ... "We're all so terrified by the prospect of a second Trump term that we've opted to ignore every warning sign. The George Stephanopoulos interview only reinforced what we saw the week before."

He also makes it clear that he loves Joe Biden and even considers him a friend he believes in, but adds ... "The one battle he cannot win is the fight against time. None of us can."

He says his opposition to Biden running is purely about age because it's "nothing that can be reversed. We are not going to win in November with this president."

Clooney calls for other Dems -- including Vice President Kamala Harris, Governors Gretchen Whitmer, Gavin Newsom, Wes Moore and Andy Beshear -- to become the focus for the Democratic Party heading into next month's convention in Chicago.

He closes the op-ed, saying ... "Joe Biden is a hero; he saved democracy in 2020. We need him to do it again in 2024."