According to some US constitutional pundits, in theory,
senators representing about 11 percent of the population can filibuster a bill or those representing about 16 percent of the population can have a majority.
As a double-check on that [rather acerbic article], an older  source, stated:
For example, in the 104th Congress, representatives from as few as nine states could constitute a majority in the House, while senators from states with little more than 10 percent of the nation's population could constitute a blocking minority under the Senate's cloture rule. The former is emphasized by senators from small states; the latter is emphasized by senators favoring culture reform.
Did such small percentages of the US population actually coalesce in a blocking minority (through their Senators) for some actual piece of legislation, though?
Basically, what is roughly [since it's probably difficult to find the absolute lowest figure] the lower bound for that percentage that has been actual encountered, historically, in successfully opposing some legislation in the Senate?
EDIT: Given the non-answer below: I know very well that officially senators represent states, two per states, to be more precise. I'm also not asking here for the reasons why the constitution is like that.
So, if you want me to be really pedantic in formulating this question: for which legislative proposal blocked in the Senate was the proportion of the population in the states blocking it (relative to total US population) the smallest? (Formulated like this the question is valid before the 17th Amendment was adopted too, even though it might not be as interesting for the period before. Also note that in the spirit in which the criticism is advanced it pertains to total state population as opposed to how many people actually voted for those Senators, which would be even harder to find out because it would have to take into account elections turnout.)
Side note: I was able to find myself an answer to a related question regarding Senate's working majority (also covered by the 1st quote I gave). As an average of all votes over the year, the low point was reached in 2017:
In 2017, the median percent of senators voting yes on legislation was a mere 54% — the lowest in at least 30 years, which is the furthest back we have this data. On these votes to pass legislation, senators voting yes represented just 47% of the country’s population — also the lowest in at least 30 years.
The Congressional Review Act’s time limit expired in 2018, and, as can be seen in the charts, 2018 looked a lot like most other years.
47% is still far off the 16% limit from the first quote I gave... but also this 47% is an average, although given the block-voting of parties behavior I doubt the extreme (that year) was very far off the 47% average.