AUDIE CORNISH, HOST:
There's one issue the major presidential candidates seem to agree on. Both Donald Trump and Hillary Clinton say they're opposed to President Obama's multi-national trade agreement known as the Trans-Pacific Partnership.
In the swing state of Iowa, many agricultural groups like the TPP because it will open new markets for exports like Iowa pork. Iowa Public Radio's Clay Masters reports from the Iowa State Fair, where agriculture and politics meet.
UNIDENTIFIED MAN #1: We got a lot of work to do so we're going to get started. But first of all, we're going to call them.
CLAY MASTERS, BYLINE: It's standing room only at the swine barn for the Iowa State Fair's big boar contest.
UNIDENTIFIED MAN #1: (Imitating boar).
MASTERS: The top prize is awarded to the heaviest pig.
UNIDENTIFIED MAN #1: One thousand, one hundred forty-eight pounds.
MASTERS: On this date, swine veterinarian Howard Hill is one of the fairgoers strolling down the concourse in Des Moines. Hill is former president of the politically powerful National Pork Producers Council. He says the Trans-Pacific Partnership is probably the biggest commercial opportunity ever for Iowa's pork producers.
Nearly one-third of the nation's hogs are raised here, many for export to Asia. Hill says Donald Trump was not his first choice for president, but he'll be voting for the nominee this fall. The two even met.
HOWARD HILL: He said that he doesn't use the term free trade because he said there's no such thing as free trade. He wants fair trade. I think that he would try to negotiate some of the things that he sees are not favorable to the U.S.
MASTERS: Hill is hopeful Congress will eventually approve the TPP. He's able to catch his congressman, Republican Steve King, after he finishes up a political speech before fairgoers. King isn't optimistic.
STEVE KING: It's been demonized like no other trade deal...
HILL: Oh, yeah. Yeah.
KING: ...We had objective discussions about other trade deals, this one's been demonized.
MASTERS: One of the politicians demonizing the TPP is Donald Trump. Here he is in Cedar Rapids last month.
(SOUNDBITE OF ARCHIVED RECORDING)
DONALD TRUMP: Trans-Pacific we're going to reject. We've got to reject. It will be as bad as NAFTA and maybe worse, and it'll very bad for Iowa.
MASTERS: Still, Steve King and all of Iowa's top Republicans have fully thrown their support behind him. Governor Terry Branstad even just signed on to Trump's agriculture advisory team. Iowa Republicans are in a difficult spot. They weren't likely to support Trump's Democratic rival Hillary Clinton anyway, and she's no fan of the trade deal either.
Back at the State Fair, Iowa's freshman U.S. Senator Joni Ernst is politicking at the pork tent while topping off fairgoers' water glasses.
JONI ERNST: Oh, I suppose that is my job today (laughter).
UNIDENTIFIED MAN #2: Thank you for all that you've been doing. Yeah. You've been great.
ERNST: No, it's my pleasure.
MASTERS: Ernst spoke at her party's convention last month, while many Republicans didn't even show up. If Trump is elected, Ernst says, she'll try to make the case for this trade deal.
ERNST: I would like to sit down with him and really explain how this is beneficial not only to Iowans but also to the citizens of the United States.
MASTERS: Leaving many Republicans in a tough position - support the party's nominee in hopes that he'll change his mind on a signature issue once he's in office. Trump will be back in Iowa later this month to headline a fundraiser for Senator Ernst, which features a pork roast.
For NPR News, I'm Clay Masters in Des Moines. Transcript provided by NPR, Copyright NPR.