What's (roughly) the smallest percentage of the US population that through its Senators has successfully blocked a piece of legislation?

Question

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 [2001] 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.)

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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.

Answer 1

Really small

The answer will be smaller than you probably think, because in the modern political landscape neither chamber tends to bother with any legislation that they don't think the majority by itself will pass. Truly bipartisan behavior, where cross-party support was required to pass, rather than just coincidentally occurred when a party-line split still would have passed the bill, is exceedingly rare these days. That's why in the current senate you always hear talk about just needing 4 Senators to join the Democrats on X, etc. etc. (and it's almost always the same 4 Senators being considered as possibilities).

As such instead of looking to bypass a cloture threshold, you really have to look at the party-line support, because bills can and often do die long before they get to the point where cloture is relevant. And in the comments CramerTV points out that bills also have to get through committees first, so a very small number of Senators can be all that's required to block certain (types of) bills.

There are three examples I can think of that fall along these sorts of lines.

The maverick (~2.2%)

One might consider the failure of the previous Senate to repeal Obamacare to be an example where a single senator, John McCain from Arizona, doomed that legislation by himself. With the current US population at around 327 million, and the population of Arizona being about 7.1 million, we have that Arizona has about 2.2% of the American populace. It seems reasonable to presume that this is approximately the same percentage of the voting populace it contains.

The Gang of 14 (.8% to 17.5%, depending on interpretation)

In the 109th Congress (2005) the Senate Democrats were frequently using filibusters to block Bush's judicial nominees. The Republicans grew tired of this and threatened to use the Nuclear Option. The Gang of 14 was a coalition of 7 Republicans and 7 Democrats. The Democrat members agreed to vote for cloture on judicial nominees (except in "extreme circumstances", a term left to each individual member to interpret), while the Republicans would agree to vote against the nuclear option. These were enough to ensure cloture would succeed with 62 votes (assuming no more than two "extreme circumstances" were invoked) and that the nuclear option would fail with only (at most) 48 votes in favor.

The total US population in 2005 was 295.5m.

The Republicans, with their states and then-populations were:

• Lincoln Chafee (Rhode Island, 1.07m)
• Susan Collins (Maine, 1.31m)
• Olympia Snowe (Maine, 1.31m)
• Mike DeWine (Ohio, 11.48m)
• Lindsey Graham (South Carolina, 4.25m)
• John McCain (Arizona, 5.97m)
• John Warner (Virgina, 7.55m)

Note that both of Maine's Senators were involved. So these Republicans collectively represented about 31.63 million people, which was about 10.7% of the US population. The three smallest representatives (the minimum number that would have to defy the agreement to invoke the nuclear option) represented just 2.38 million people (as the three includes both Maine senators), or about .8% of the populace.

The Democrats, with their states and populations, were

• Robert Byrd (West Virginia, 1.80m)
• Daniel Inouye (Hawaii, 1.26m)
• Mary Landrieu (Louisiana, 4.49m)
• Joe Lieberman (Connecticut, 3.48m)
• Ben Nelson (Nebraska, 1.75m)
• Mark Pryor (Arkansas, 2.78m)
• Ken Salazar (Colorado, 4.66m)

So the Democratic members represented a total of 20.22 million people, or about 6.8%. The three least populous states represented (the minimum number that would have to defect from the deal for cloture to fail) contain just 4.81 million people, or about 1.6% of the total population.

The full gang represented about 17.5% of the American population, and successfully thwarted the leadership of both parties on the issue (but only for that one Congress).

This is, however, not actually legislation. But confirming judges is at least a core constitutional power and responsibility of the Senate, and cloture rules have been very important to them in recent memory.

The Grim Reaper (~1.37%)

The Senate Majority leader sets the schedule of the Senate, and so can unilaterally decide which pieces of legislation get debated and which do not. And Mitch McConnell is presently doing exactly that (not that other Senate or House leaders from both parties hadn't done it before him). Mitch McConnell is currently happy to call himself the Grim Reaper, and that the Senate is a graveyard for the legislation passed by the Democrat House. Mitch McConnell represents Kentucky, population 4.47m, which is less than 1.4% of the current US population.

Answer 2

Zero

The entire chain of reasoning behind the question is wrong because Senators do not represent population. The Senate exists to represent the interests of states themselves, which were assumed could be entirely different from the people living in them.

Even if we ignore that distinction, Senators were not even directly elected until 1913, so it changes what "populations" are relevant to the question

Prior to that point, Senators were selected by state legislatures, using whatever criteria they wanted. If it is desired to focus on this population based argument, then the population in question being represented shouldn't be the entire population of a state, but of the legislature.

Given that a large state legislature has at most hundreds of members, and the United States had a population of about 4 million people in the 1790s, then the upper bound on the value can be approximated by (200 x 13)/4 million, or 0.25%. Which I would argue still rounds down to zero.