DES MOINES, IOWA — When Bernie Sanders stepped onto a makeshift soapbox at the Latino Heritage Festival here Saturday, he immediately compared himself to Pope Francis.

"What he is saying in so many words is there is something very wrong in this world, and I am saying in this country, when so few have so much and so many have so little," Sanders said.

It would be easy to interpret Sanders's emphasis on Francis, who just wrapped up a US tour, as the fleeting fascination of a politician trying to capitalize on a zeitgeist. It would also miss the point.

What Sanders is really doing is defter and more interesting — he's using the pope to put his unusual-for-America politics into a global context that makes them seem more mainstream to voters. Francis, who recently admonished world leaders to "seek a new economic model to help the poor and to shun policies that sacrifice human lives on the altar of money and profit," helps him do that.

Surely it isn't hurting. Few took Sanders, an avowed socialist, seriously when he announced his candidacy. America just doesn't do socialism. But an NBC/Wall Street Journal poll released Sunday morning shows Sanders pulling within 7 percentage points of frontrunner Hillary Clinton, at 42 percent to 35 percent, when Vice President Joe Biden is included in the list of choices.

"God bless Pope Francis," Sanders said in Phoenix in July. "I think sometimes people think my economic views are radical. You should hear what this guy is saying."

"He's not pandering"

In January, Time magazine wrote that although Sanders is Jewish, "he’s also the likely 2016 presidential candidate whose political philosophy lines up most closely with the economic and social theories of Pope Francis."

That's quite a statement, given that at least a half-dozen of Sanders's Republican and Democratic rivals for the presidency are actually Catholic. But Sanders — more than any other candidate — has long seized on the words of the pope to highlight his own worldview, particularly on the distribution of wealth, immigration, and climate change.

His Senate website points to an ABC news account of "10 times Bernie Sanders and Pope Francis sounded alike"; he sent donors a solicitation last week headlined "Why we must listen to Pope Francis"; and he invoked the pontiff during a speech at the evangelical Christian Liberty University earlier this month.

It's usually smart for a politician to hook his star to a more popular and well-known public figure. While only 40 percent of Americans view Sanders favorably, 63 percent see Francis that way. Moreover, Sanders can benefit from an association with Francis without worrying, as a Catholic candidate might, that voters will think he's too close to the Vatican. Instead, he is free to hold up the pope as a moral leader — and one who makes Sanders's self-described socialism seem less extreme.

"He's for the poor, too, just like the pope," Lloyd Levine, 62, said after Sanders spoke at the Latino Heritage Festival. "He's not pandering. He just agrees with the pope."

How Sanders and Francis sound alike

The pope sounds so much like Sanders — and vice versa — that Sanders's Democratic colleagues patted him on the back and shoulder several times during the pontiff's address to a joint meeting of Congress last week, according to one person who witnessed the congratulatory gestures.

The main connective tissue between the Jesuit pope and the socialist presidential candidate is a view that the powerful have a responsibility to the powerless, including a planet that needs defense against manmade toxins. That plays out on a variety of issues, but most important for Sanders on wealth. The pope's strong condemnations of the pursuit of assets at the expense of the masses make Sanders look at least a bit more tolerant of capitalism.

"Jesus affirms that you cannot serve two masters, God and wealth," Francis said earlier this year. He also has called for "the legitimate redistribution of economic benefits by the state, as well as indispensable cooperation between the private sector and civil society."

Sanders referred to the pope at all but one of his six stops on a two-day swing through Iowa, including at a Jewish Federation meeting in Waukee, where he cited Francis's admonitions about climate change.

Here's what Francis said on the House floor: "I call for a courageous and responsible effort to "redirect our steps' and to avert the most serious effects of the environmental deterioration caused by human activity. I am convinced that we can make a difference, and I have no doubt that the United States — and this Congress — have an important role to play."

And here's Sanders on the same topic in his launch speech: "Climate change is real. It is caused by human activity, and it is already causing devastating problems in the United States and around the world. ... The United States must lead the world in reversing climate change."

Francis's popularity is encouraging to Sanders, as it can be read as evidence that the world wants a more morally charged critique of capitalism's excesses, a critique that Sanders is unusually eager to deliver.

A few weeks before Francis's visit, Sanders spoke at Liberty University — a bastion of religious conservatism, and an unusual venue for a socialist to deliver a major campaign address. But Sanders, who referred to Francis repeatedly in that speech, clearly wanted to try out the message on a different audience.

"We are living in a nation and in a world, and the Bible speaks to this issue, in a nation and in a world which worships not love of brothers and sisters, not love of the poor and the sick, but worships the acquisition of money and great wealth. I do not believe that is the country we should be living in," he said. "Money and wealth should serve the people. The people should not have to serve money and wealth."

The transcript records what happened next. It says, simply, "APPLAUSE."