Left: Bernie Sanders speaking in Iowa on Monday night (Lucian Perkins/The Washington Post); Right: Ted Cruz also speaking in Iowa on Monday night (Cassi Alexandra/The Washington Post)

DES MOINES — Here is a stark reality for both Ted Cruz and Bernie Sanders voters: Should your candidate win the presidency, he will disappoint you. Both candidates have whipped up voter passions by offering ideologically comforting — and strikingly similar — narratives promising political revolution. Both would fail to achieve such a momentous national transformation because popular opinion and the country’s system of checks and balances would get in the way. (See the Obama presidency.)

So why are people swooning for them? According to entrance polling, Cruz racked up votes from Iowans who prioritized finding a candidate who “shares my values,” and Sanders got a lift from those looking for a candidate who “cares about people like me.” This is partially because both candidates are telling bits of their parties’ bases what they want to hear. But another reason is that they have the “credibility” that comes from spending years angering “establishment” politicians — that is, people who have been sullied by having to govern in the real world of constraints and tradeoffs. Years of screaming from the fringes, refusing to deviate from a simplistic message as others ran the country, have given both men a massive political asset in 2016 — “authenticity” — and that quality alone is attracting people, particularly those who suspect that elite corruption or conspiracy is responsible for the country’s problems. 

Cruz constantly plays the authenticity card. In Iowa he appeared before a banner reading “TRUSTED” — with colored lettering that made it read more like “Trust Ted.” Below that were the words, “courageous, conservative, consistent.”

Cruz and attendees at his rallies complain that Republicans elected leaders in the past who failed to deliver. “I don’t vote for RINOs anymore,” said Bo Dostal, a Kansas City resident who drove four and a half hours to see Cruz speak in Ames, Iowa on Saturday. “It’s Teddy or no one,” he explained. “He has done everything he said he was going to do.”

“The problem right now is that we have a lot of old timers” in Washington, Nancy Gargan said after watching Cruz in Ames. Cruz, Gargan said, would make the old timers and their lobbyist cronies “cower down.”

Cruz and his acolytes blame corruption or weakness for the failure of Republican leaders to make good on the conservative agenda — rather than the fact that those leaders had to govern a country that is not as conservative as they are and that faces challenges that lack pat solutions. Their misapprehension leads to perpetual anger — and, as a result, to perpetual gridlock.

On the other side of the political spectrum, Sanders offered Iowans his own, simple story about the source of America’s problems — widespread corporate-political corruption — baked into which is the implication that practically everyone else is less sincere than he is. The message is that others are not like him because someone is paying them off.

This is working.

Martha Avelleyra Powers gushed about Sanders just before he took the stage in Iowa City Saturday night: “He’s authentic, he’s real, he really gets people like myself,” she said.

“This is a once-in-a-lifetime candidate,” Vampire Weekend frontman Ezra Koenig exclaimed as he warmed up the crowd of Berners. “We don’t see someone like this all the time, somebody who is independent for 30 years. We don’t see people who say the same thing over and over again.”

The next day at a Hillary Clinton rally across the state, Rick Devos shrugged toward the stage. “Relatability,” he said, “with Clinton it’s just not quite there.” Though he had concerns that Sanders does not have a real plan for “how he’s going to get things done,” Devos was leaning toward Sanders. After the rally, things did not look good for the pragmatic Clinton. Did she change Devos’s mind? “No.”

Among backers of both candidates there is a sense that, even if their man does not pull off a full political revolution, at least they can be confident he would push as hard as he could to pull the nation as far as he could in their direction. At least Cruz “is going to start out on the foundations I believe in,” Denise Hayes said while wearing a Cruz football jersey at his rally in Ames. In this view, policy specifics and political realities do not necessarily matter as much as — yep — authenticity.

But political puritans such as Cruz and Sanders tend to make policy the way they explain the world — with unwarranted, clumsy simplicity. In his not-quite-victory speech Monday evening, Sanders, for example, characteristically attacked critics for harboring hostility toward progressive goals, such as universal health-care, when many really object to the poorly-crafted plans he has to achieve them. Even hardcore progressives who have scrutinized Sanders’s program recognize that it is not just politically impossible — it proposes a massive economic transition based on excessively optimistic budgetary assumptions. Cruz’s plan to carpet bomb Syria, meanwhile, does not even require close inspection to conclude it is shallow. These are among the indications that they would not bring good instincts to the real, harder decision-making that comes with the Oval Office — even if you agree with moving in the general direction one of them wants to go.

Authentically believing that the whole country secretly agrees with your agenda and will join you on the barricades is not a virtue, it is a fantasy. Sincerely proposing poorly thought-out policy does not change the fact that it is poorly thought-out policy.