Getting back on topic...
The current Senate rules allowing for filibuster only require that one senator raise an objection to closing the debate. That senator doesn't have to hold the floor, such as Senator Jefferson Smith did in 1939 (
link). Our modern day senator's objection holds unless 60 senators vote for cloture, ending the debate. As such, it takes only 41 senators representing roughly 21 states to sustain a filibuster.
Bear in mind that the smaller states all tend to have Republican senators and that the larger states all tend to have Democratic senators. You can find exceptions (Texas and Florida for Republicans, Vermont and Delaware for Democrats), but the bottom line is that a Republican Senate filibuster can be maintained by the 21 smallest Republican-represented states that hold only 63 million people, while a Democratic filibuster is maintained by 21 smallest Democratic-represented states that hold 126 million people.
I get that the Senate is supposed to provide smaller states a larger voice at the federal level, but doesn't the current method of filibuster go to far? And isn't it obvious that the Republican states derive a much larger benefit than the Democratic states?
Is there a middle ground here? One that's between maintaining the effective veto power of senators representing only 20% of the population and eliminating all protections for those smaller states?