Manchin’s the dem holdout but let’s talk about why Senators want to keep the filibuster:
First, the Senate was never meant to be “the world’s greatest deliberative body.” It is simply a second body that gives states equal representation. That’s it. The House represents the people’s interest, the senate represents State’s interests. (The Executive Branch represents the Nation’s interest and the Courts the Republic’s interest.)
Second, the filibuster effectively gives individual Senators veto power on par with the President’s. This power super charges individual senators power in the government and that increases all of the donations and influence you can imagine. Think of how much the gun lobby will pay one Senator or the oil lobby. I’m sure you all get it, they only need one Senator in their pocket to stop any legislation they don’t like.
Lastly, this effects republicans and democrats the same. Neither party can get their agenda through congress and that includes repealing laws. So we are stuck with an unresponsive government with outdated laws instead of having a government that can actually try all kinds of different things and change whatever doesn’t work.
TLDR: the filibuster is a scam that gives individual senators veto power that was only meant for the executive branch and senators benefit from this power through donations and influence.