Potential Republican candidates for president in 2016 gathered in Des Moines for an eight-hour summit Saturday, discussing a wide-range of topics and scoring points with Iowa agriculture insiders and voters.

Among the potential candidates who appeared on stage with wealthy agriculture entrepreneur Bruce Rastetter — a major GOP donor in recent election cycles — were former Florida Gov. Jeb Bush, Wisconsin Gov. Scott Walker, Texas Sen. Ted Cruz, South Carolina Sen. Lindsey Graham, along with several others.

Others who ran in 2008 and 2012, and are likely to launch second bids for the White House, also appeared at the event, including former Arkansas Gov. Mike Huckabee, former Pennsylvania Sen. Rick Santorum and former Texas Gov. Rick Perry.

Along with major agriculture themes not often discussed in presidential elections, the Renewable Fuel Standard (RFS), which mandates how ethanol and biodiesel are blended into fuel, was a topic brought up in almost every candidate appearance.

It may also be the issue that divided candidates the most, with Bush, Huckabee and Santorum defending it on stage, while Cruz and former New York Gov. George Pataki voiced opposition to a federal mandate on the RFS.

“The answer you’d like me to give is that I’m for the RFS,” Cruz told Rastetter on stage. “I’ll tell you, people are pretty fed up with politicians who run around telling one group one thing, another group another thing, and then go to Washington and they don’t do anything they said they’d do.”

Iowa Gov. Terry Branstad, an ardent supporter of the RFS who has said he’ll encourage candidates to support the standard, gave a speech on stage to open the gathering.

“Don’t mess with the RFS,” Branstad told the crowd of about 900 attendees, garnering a loud applause.

Immigration, a major source of labor in the agriculture industry, has split the more moderate and conservative members of the Republican Party and was an issue at center stage during the event.

Graham, who was a supporter of the comprehensive immigration bill that passed the Senate two years ago, but stalled in the House, has split with his party on the issue.

“It’s hurting the party, it’s a national security nightmare, it’s a cultural problem,” Graham said. “We need immigration reform that will supply us the labor to keep rural America working.”

Bush, also a supporter of overhauling the immigration system, called for legalized status to those already living in the United States illegally.

“Immigrants that are here need to have a path to legal status,” Bush said. “Nobody has a plan to deal with illegal immigration other than to just say they’re going to be rounded up and taken away.”

Huckabee differed with Bush and Graham when Rastetter asked him how immigration labor fits in with an overall immigration policy.

“It fits in just fine, as long as the immigrants are legal,” Huckabee said. “It doesn’t fit in at all if you import illegal people to come in and take jobs.

“A country that does not have secure borders is really not a country anymore,” Huckabee added, calling for more border security at the southern border.

Walker received a positive response from crowds when asked about government benefits like food stamps. Walker noted his state has requirements such as those on assistance must be signed up for job training programs.

“The people in Madison, my state capitol, some of which are a little more liberal than we are, say that when I propose things like work requirements and employability training for food stamps, that somehow we’re making it harder to government assistance,” Walker said. “I’ve got to tell you we’re not. We’re making it easier to get a job.”

The event was also interrupted several times from protestors, once during Branstad’s speech and again during Christie’s speech.

“My people follow me everywhere,’ Christie told Rastetter, referring to protests that have become common at New Jersey events. “I’m magnetic, Bruce. They can’t stay away from me.”

Other common issues brought up include energy and farm subsidies, overreach in executive and agency powers, GMO labeling, water pollution, trade with Cuba and bio technology.

The event’s lineup seems to have gone over well with those in attendance, with potential candidates not just giving stump speeches and pausing between applause. But participants were still out to impress Iowa voters.

Cruz spent almost a half hour talking to media, shaking hands and taking pictures with attendees following his speech.

Graham and Santorum made several media appearances for local media in the Des Moines market.

The event was not without some zingers.

“I’ve enjoyed being in Iowa,” Graham said to the crowd. “But how the hell did y’all vote for Obama twice? Don’t do that again!”

For coverage on each specific speech from all the potential candidates, statewide Iowa officials and Representatives from Iowa in Congress, read the Daily’s live coverage page here.