This post is part of Polyarchy , an independent blog produced by the political reform program at New America , a Washington think tank devoted to developing new ideas and new voices.

Perhaps you have been following the presidential campaign so far and asked yourself: Really, are these all the choices we are going to get for president? Why are they all so, how should we put it ... inadequate? Mediocre? Disappointing? Or just plain bad?

Or, more succinctly: Why can't we have better candidates?

Here are four reasons why.

1) It's the media: They want to tear down the candidates and sensationalize the process.

The media, as the self-appointed public watchdogs, see their role as vetting all serious candidates. Some of this means looking into the candidates' records and histories to expose the inevitable hypocrisies that life foists upon all of us. But more and more, it involves constantly trying to catch the candidates off guard with "tough" questions, trying to show the public why so-and-so might not be fit for office because he or she doesn't have something snappy to say on the spot about the latest developments in Syria.

For candidates, there's no good choice. Avoid reporters (like Hillary Clinton has done), and they will get angry and write stories about how secretive you are. Open yourself up to the media, and you will wind up saying something that came out wrong (like, most recently, Jeb Bush using the word "retarded"), thus giving the press what it craves most — fodder for several days of probing, low-grade lexical analysis.

The media also wants very much for a campaign full of good stories. A good story is a candidate who says something outrageous. A good story is a competitive, divisive primary. A good story is the loudmouthed Donald Trump versus the Republican establishment.

While there are certainly many reasons for Trump's success, one is that, as one television journalist friend told me, "he rates." That is, his showman presence draws in viewers. If candidates have to out-Trump Trump to get the media attention necessary for polling success, this bodes poorly for candidate quality.

News media are devoting more resources than ever to covering this campaign. That means more news media with a vested interest in this being a wild and competitive race, a good story. It also means more reporters looking for the big scoop that distinguishes them. Which means more investigations and more pestering questions.

Mainstream news media coverage of both major presidential candidates in 2012 was more negative than positive, but social media was even more negative. Social media is becoming even more important. This does not bode well for the future tenor of coverage. Of the Republican field, only the relative unknowns Ben Carson and Carly Fiorina right now have net favorable ratings. But give both of them time.

Certainly, we don't want our press to be purely adulatory. We don't want to live in North Korea or Soviet Russia. A watchdog press plays a key role in democracy. But a watchdog that barks "wolf" every minute starts to lose credibility after a while.

2) It's the process: It's too long. It's too negative.

Back when I was more in the business of dispensing relationship advice (most of my friends are married now), I was fond saying you shouldn't move in with your significant other until you were ready to marry that person. My rationale was simple: If you move in together as a test run (as many people do), you will spend your time scrutinizing your potential spouse to make sure she/he is worthy. When you scrutinize too much, you see faults. When you focus on the faults, you see deal breakers.

If we spend almost two years looking at these candidates mostly trying to find fault with them, it's no wonder they start to look pretty bad. It's a long, drawn-out electoral process, by far the longest in the world. It creates a long and brutal struggle that can't help but make most of our candidates look worse for all the wear.

On top of an increasingly aggressive media looking for faults (see reason No. 1), we also have the growing din of negative advertising. With each election, there is more money spent on advertising, and more of that advertising is negative. The 2012 presidential election was by far the most negative on record, with more than 80 percent of ads classified as negative. Like presidential races, House and Senate races have also grown more and more negative over time, in part because more and more money is coming from outside groups.

Like houseguests and fish, candidates start to stink after a while, especially when everything in our campaign media system is designed to tear them down.

Certainly, we should have some reasonable time to evaluate and assess our candidates. But that period should probably be closer to two months than almost two years.

3) It's us, the voters: We want too much. And we contradict ourselves.

What do we want in a president? Pretty much everything. As Brendan Nyhan is fond of pointing out, we want a superhero. A Green Lantern. "We like to pretend that presidents exert vast control over the country," Nyhan wrote recently, "commanding not only the direction of American politics but also the laws and policies of the country and even the state of the economy."

So we build up these ridiculous expectations. Every Republican genuflects before the ideal of Ronald Reagan, but with each passing year, the ideal of Ronald Reagan (slayer of communism, fighter for freedom, ruthless champion of small government) becomes more and more separate from the reality of the actual Ronald Reagan (whose record of raising taxes, tripling the debt, and negotiating with dictators now borders on apostasy to Republican Party values.)

Of course we don't like our candidates. They can't be who we want them to be because we want things that, collectively, are not possible. We say government is too big, but we like all of its programs. And who's to tell us we can't have it all? Only somebody who doesn't know how to overpromise in a way that will ultimately disappoint us. Also, we are collectively in a pretty foul mood these days. We're a tough crowd to please.

Moreover, as an electorate, we are actually even more divided than the simple red-and-blue nation dichotomy implies. Sometimes we think about this in terms of the "primary" voters versus the general election voters, with the primary voters seen as being more ideological. But this isn't quite right. Both parties are actually broad coalitions, with much internal disagreement. As we've learned from this year's Republican primary, the GOP consists of populists, Christian conservatives, business Republicans, and libertarians, all with different views on what the Republican Party ought to stand for. While Democrats tend to be less ideological, the Warren/Sanders supporters have views that Hillary Clinton can never represent. The electorate is far more diverse than our two-party system would lead us to believe.

To please all these diverse voters means having to speak in bland generalities that please nobody. But pleasing some people means offending others, and thus giving up some of your support. There's no good choice.

Every now and then, a candidate can tap universal ideals like "hope" and "change" and become an empty vessel for a broad party coalition. But this is hard to do, and it mostly relies on a combination of personal biography and a very unpopular incumbent who can be the focus. Most candidates can't pull this off.

In a multi-party system (as featured in most other advanced democracies) the different wings of our current party system could each have their own parties and their own standard-bearers. They would then form governing coalitions to work together, based on the share of the electorate they represent. In the US, they wind up fighting each other for control of the two majority parties through the primary system.

As long as we want many different and contradictory things out of a candidate because we are, after all, a diverse and sprawling nation of 319 million people (the third most populous in the world), it is very difficult to find a single candidate who can reasonably claim to represent even half of those people. At best, such a candidate can be an empty vessel. But see reasons 1 and 2 for why it's harder and harder to be an empty vessel.

4) It's the candidates: They are all insane.

Finally, given reasons 1, 2, and 3, you need the following to run for president: an ego so big as to be pathologically narcissistic, a skin so thick as to be entirely indifferent to what others think, a willpower so cyborg-like that you never let down and say the wrong thing, and a patience so remarkable that you can tolerate each and every idiocy of the never-ending process of campaigning.

In other words, you pretty much have to be insane. No wonder our candidates are all so bad.

Can anything be done?

All institutional choices in politics involve trade-offs, some of which are more apparent than others. A watchdog press is an essential element of democracy. But if I had a watchdog that barked aggressively and constantly no matter who showed up at the door, I'd get a new watchdog.

A competitive vetting process is valuable. But spend two years looking for faults and even God might come out looking bad. ("Sir, you said in John 8:36, and I quote, ‘If the Son makes you free, ye shall be free indeed.' Yet a lot of parents don't feel free right now, given their struggles to afford child care in the current economy. What would you say to those voters?") I'd say the optimal campaign season would be closer to two months.

Yes, we, the voters bear some of the blame. We ask too much of our candidates. But they've also overpromised, raising our expectations. And yes, maybe we are too diverse in opinion for any candidate to please even half of us. But until we get a multi-party system, we're going to have to learn to put our differences aside better.

In the meantime, who wants to run for president, anyway? You have to be crazy.