Roosevelt had a huge majority in Congress after the 1936 election. He secretly made plans before announcing his court-packing attack on the very fabric of democracy. After one of the most viscous debates in US history, the Senate finally withdrew the bill, with cries of "Glory to God" coming from one of the senators.
Biden can have this debate again. The result will be a year (6 months of investigations and hearings, and 6 months of heated debate). The leftists have what they want, a debate on one of their sacred principles.
In the meantime, little will get done once the report comes out, and win or lose, the Democrats will have reduced the number of senators elected in 2022. This will not affect elections is very blue districts in the Senate and the House. Progressive Democrats will not lose their seats. As was the case in 2020, it is moderate Democrats who will pay the price. [We do remember that Republicans gained seats in the House and would have controlled the Senate absent Trump's antics in Georgia]
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THE BOTTOM LINE
is that Biden is pushing hard and as quickly as possible to pass as much as he can before ONE or TWO Democrats stop supporting some of his legislation.