Why hasn't the left been able to rally support around opposition to domestic spying?

Tea Party candidates on the right have been able to generate excitement among GOP base voters with their calls to end the National Security Agency's domestic spying program. Senator Rand Paul appears to have staked his entire potential presidential campaign on a brash defense of personal privacy (except when it comes to abortion). Libertarian-leaning Republicans in the House have been unapologetic in their criticism of the program, their own energy magnified by near-unanimous support from conservative talk radio and bloggers.

Those advocates of civil liberties (some of them quite new to the cause) have a convenient explanation for why Democrats have been less vocal and slower to criticize the collection of metadata from everyday American citizens: slavish devotion to President Obama, whatever policies he might champion.

This is an easy argument to make – and it goes both ways. Pollingamong Democratic and Republican voters shows a mirror-image of approval for Obama's use of the tactic to Bush's use of it. Since 2002, the number of Democrats who approved monitoring online activities has increased 12 points; among Republicans it has decreased 13 points. Since 2006, the number of Republicans who say the government should prioritize privacy over hunting terrorists has risen 22 points; Democrats who say the government should prioritize preventing terrorism over privacy has gone up 18 points.

The neatness of these changes in position is almost disturbing. It suggests that advocacy for civil liberties is a zero-sum game: there's only so much libertarianism to be had at any given historical moment, there's a ceiling on Americans' ability to believe that the right to privacy is paramount. Indeed, as you might suspect from the numbers above, polling among all Americans on the balance of national security to privacy has neatly flipped as well. The percentage of voters that worry that the US will go "too far" in violating privacy rights in pursuit of terrorists versus "not going far enough" is now 56% percent versus 36%. In 2001, after the 9/11 attacks, it was 31% versus 55%.

It's these numbers, rather than the occupant of the White House, that explains Democrats' reluctance to move very aggressively in championing personal privacy – or, at least, it explains the difficulty in creating a lasting coalition around it. If at best, you will only get half the country to agree with you – and what's more, different phrasing of the question or current events context shows inherent wobbliness on the issue – what politician will stick out his (or her) neck over it?

Already, the roster of 2016 presidential candidates illustrates the ambivalence of those who would like retain "electable" and "moderate" as part of their bio. While the skirmish between Chris Christie and Paul over terrorism and its prevention via surveillance got a lot of media attention this week, it's more helpful to look at the general trend among potential candidates. There, with candidates in both parties, the message on warrantless wiretaps and email surveillance is instructively equivocal – or, rather, clearly unclear… and the view gets more hazy, the greater the likelihood of the candidate.

Hillary Clinton, for instance, has done an elegant disappearing act with her views. She has gone from a vocal critic to silent beneficiary of the same programs. Once loud-mouthed Joe Biden has been just as mum.

On the right, Marco Rubio refuses to condemn the process, only saying:

It's a struggle to balance our deeply held convictions of privacy and freedoms and liberties with our need to provide for national security.

Governor Bobby Jindal does the same kind of hand-wringing, sayingonly that the balance between promoting a smaller government and national security issues is a debate worth having.

Senator John Thune and former House member, now senator, Rob Portman speak with the same precise restraint. Former GOP vice presidential nominee Paul Ryan straddles the divide more obviously; he told reporters that the NSA practices were "creepy" but voted to continue funding them.

On the left, even Senator Elizabeth Warren – generally presumed about as far left as a mainstream candidate can go – has called simply, safely for "an informed discussion". Most of the governors in the running (and most of the named prospective candidates are governors) have been spared having to comment on the controversy at all.

I have a lot faith in Americans' inherent distaste for government intrusion into their lives. My theory of American civil rights has always been that we move forward, and sometime backward, to the exact degree that a majority of Americans can be convinced that the issue is fundamentally about being left alone to live one's life with minimum snooping or control from anyone. It's true for marriage equality, reproductive rights, providing a path to citizenship for illegal aliens, the tenacity of Second Amendment beliefs, and an argument can be made that the protection of voting rights can be manipulated to either side's advantage along these lines as well: we just don't like to see our fellow citizens hassled. (Conservatives show footage of Black Panthers at the polls, progressives harken back – not very far – the obstacles white legislators put in front of black voters.)

The problem with applying this theory to the right to private communication, virtual assembly, and expression is that we don't seethe oppression very much. You cannot hold up a picture of someone being electronically spied on; even worse, you cannot illustrate the psychic damage and cowed sensibilities that come with the fear of being spied on. Undermining the cause further is that to champion civil liberties is, in a way, to champion inaction. Politicians cannot say, "I did this thing for you," they have to say, "I did not do this thing." Yes, to a certain slice of voters that is the exact message that propels them to the polls; a large majority of Americans what to see things happen.

Yes, advocates can hold up examples of the police power run amok. I think this even works, a little. More Americans see Edward Snowden as a "whistleblower" than a criminal, for instance. But it takes an act of muscular imagination to transfer his experience to one's own.

Compare this to the visceral reaction one has to images of a terrorist attack. The immediate sense that "it could have been me". And as for how terrorist attacks engender the desire for protection – a very particular kind of action by authorities. And the heroics stances that politicians can make when they say that they have saved you!

It is cynical but true that one reason 2016 candidates have refrained from speaking too loudly on domestic spying is their understanding of this very dynamic. One bomb, one devastating video, one instance when our agencies can prove a near-miss and a denouncement of surveillance becomes a millstone and not a platform.

An attack could produce the desperate acceptance of a security state in an instant. But it is difficult to imagine the incidents that would spur momentum towards a broader movement for and understanding of the right to privacy. And if you can imagine America coming to that – whether it looks like 1984 or Singapore – well, by then it will be too late.