Before dropping out of the Republican presidential race, South Carolina Senator Lindsey Graham is reputed to have learned two things campaigning in Iowa: You need to love Jesus and ethanol.

Religion plays a major role in the Midwestern state's Republican caucuses. In 2012, nearly 60 percent of those who participated identified as evangelical Christians.

Iowa is the first state to actually vote for the potential US presidential nominees. A strong showing can lend credibility to an unorthodox presidential campaign.

This could explain why billionaire Donald Trump - not famous for his religious convictions - made a speech at the world's largest evangelical Christian university two weeks before the Iowa caucuses.

Trump's speech at Liberty University secured him the endorsement of the school's president, Jerry Falwell Jr., whose father was one of the most influential evangelical preachers in modern US history.

It's unclear whether or not Falwell Jr.'s endorsement will give Trump a boost in Iowa.

"Trump has kind of a question mark there in terms of his appeal with the evangelical voters in the state because of his regard for religion," Donna Hoffman, an expert on the caucuses at the University of Northern Iowa, told DW.

"He did attend a church service - that was well documented recently," she said.

The ethanol lobby

If religion is big politics, then ethanol is big business in Iowa. The state produces 3.9 billion gallons of the biofuel annually, 27 percent of the total US production.

"He's opposed to ethanol and biodiesel," Governor Terry Branstad told a press conference. "And we have tens of thousands of jobs and a lot of farm income dependent on that."

The Texas senator does have solid evangelical credentials. Unlike Trump, he has consistently opposed gay rights and abortion. His father, an evangelical preacher, has also taken to the campaign trail.

"Cruz's strategy is based on the claim that there's an entire cache of missing evangelical voters who haven't voted in the past because no candidate has been sufficiently Christian and conservative for them," Dennis Goldford, an expert on the Iowa caucuses at Drake University, told DW.

Democrats: pragmatic or progressive?

On the other side of the political aisle, it's the progressive Democrats who tend to turn out in large numbers. According to a recent Des Moines Register/Bloomberg Politics poll, 43 percent of likely Democratic caucus-goers identified as socialists.

They are also less religious compared to the Republican caucus-goers. In the same poll, 30 percent of Democrats identified as devoutly religious, compared to 62 percent of Republicans.

Bernie Sanders, a self-described democratic socialist, has given centrist Hillary Clinton a run for her money in Iowa. The two candidates are in a statistical dead heat. In October, Clinton led Sanders by a 40-percent margin in one Monmouth University poll.

Sanders' forceful message, railing against the "billionaire class" and vowing to fight income inequality, has captured the moment. But many voters value Clinton's broad experience as first lady, senator from New York and secretary of state under President Obama.

"The Democrats, at least in looking at some of the polling that's been done, have been focusing a little more than the Republicans on electability," Hoffman said. "Bernie has an appeal, but Clinton has the experience. There's a pragmatic streak to Democratic caucus-goers."

Clinton has also presented herself as the natural heir to Obama, who remains very popular with Democrats if not with the broader American public.

Getting out the vote

Only registered Republicans and Democrats can participate in the caucus system, and they tend to be party stalwarts. According to Hoffman, much of Trump's support appears to come from Iowans who have never participated in the caucuses before.

"It does appear that Trump has some appeal, both at the national level but also in public opinion polls in Iowa," Hoffman said. "But it's difficult to poll caucus-goers."

The open question with Trump "… is whether those people support him enthusiastically enough that they'll actually go," she said.

As in the case of Trump, Sanders is appealing to many people who haven't participated in the process before. Though he's polling well, it's unclear if that will translate into turnout on caucus night.

According Goldford, there was no increase in voter registration among Democrats and Republicans from July through December, which doesn't bode well for Trump and Sanders. But the numbers for January are not in yet, which means anything is still possible.

"There's more of an outsider theme this year, which raises the question whether this is an unusual year," Goldford said. "That's what we're waiting to find out."