PAWLEYS ISLAND, S.C. -- "I want you to understand: I will not promise you something that I cannot deliver," Hillary Clinton told a rally here in South Carolina. "I will not make promises I know I cannot keep. We don't need any more of that."
No, we don't. The disillusionment with politics and government now plaguing the election process has been badly aggravated by politicians in both parties making promises they knew they could not keep. And this epidemic of cynical simplification is getting worse.
Whether it's Donald Trump and Ted Cruz, vowing to deport 11 million undocumented immigrants, or Bernie Sanders rhapsodizing about a "political revolution" that will somehow change the nature of Washington, the campaign trail is flooded with fantasies that will never, ever happen.
And yet the electorate seems hungry for those unrealistic and unachievable answers. More pies keep getting tossed into more skies -- and more voters keep gobbling them up.
These voters are displaying a profound misunderstanding of two key elements of American democracy. The first is that elections matter and, therefore, so does electability. You cannot enact your program if you cannot win. And yet only 12 percent of the voters in both New Hampshire primaries cited electability as an important factor in making their choice.
The second element kicks in once elections are over. Our political system was deliberately and brilliantly designed to distribute power, to slow down the process, to require negotiation and consensus.
Easy and extreme slogans -- like "Expel the foreigners!" or "Soak the billionaires!" -- make great bumper stickers and applause lines. But they are not useful guides for governing the country.
Governing is messy and complicated. It requires accommodation, not anger; determination, not delusion. But the overpromisers undermine that system and make compromise -- the essence of democracy -- much more difficult.
Take immigration. The idea propounded by many Republicans, that undocumented immigrants can somehow be seized and sent home, is totally impractical and morally reprehensible. That policy would rip apart millions of families while undermining key sectors of the economy. Thousands of jobs, many of them in the service sector, would simply go undone.
Moreover, these proposals play on the worst phobias that always lurk just below the surface of American life: the fear of "others," the irrational and ignorant belief that America is now perfect and the next wave of newcomers will somehow deface and degrade our culture.
Or take health care. Sanders' proposal for a hugely expensive, government-run program of universal coverage is equally unsustainable. President Obama used every ounce of political capital to push through a much more modest program of expanded health insurance, and even then failed to attract a single Republican vote.
The argument that this country is even close to ready for what Sanders proposes willfully refuses to recognize that stark lesson. As the Washington Post put it, the senator's "self-regarding analysis implies a national consensus favoring his agenda when there is none and ignores the many legitimate checks and balances in the political system that he cannot wish away."
In addition, Sanders is deeply disingenuous about what his proposal would actually cost. According to "left-leaning economists" interviewed by The New York Times, his plan would "cost twice what the senator ... asserts."
"The numbers don't remotely add up," concludes Austan Goolsbee, formerly Obama's chief economic adviser.
Candidates on both sides are also overpromising when it comes to replacing Justice Antonin Scalia. Most are outlining "litmus tests" and guaranteeing outcomes -- an end to Obamacare, for example, or a reversal of the Citizens United decision that demolished the campaign financing system.
But as conservatives have learned with Chief Justice Roberts, a lifetime appointment can liberate a judge -- freeing him or her from an obligation to adhere to ideological orthodoxy.
The outbreak of overpromising didn't start this year. Tea partiers told their followers that if they were elected to Congress, conservative canons would become law -- a fanciful prospect that disregarded the basic power balance in Washington that they could not "wish away."
Obama campaigned on creating a new era of "hope and change" that would unify the country, but in his recent State of the Union address, he conceded: "It's one of the few regrets of my presidency -- that the rancor and suspicion between the parties has gotten worse instead of better."
Realism is a hard sell. What do you put on the bumper sticker? "Dynamic moderation"? "Passionate pragmatism"?
But the realists have to keep trying anyway. Otherwise, the disastrous cycle of overpromising and underperforming will continue to fuel voter despair and disillusionment.