By P.J. Huffstutter and Tom Polansek

CHICAGO (Reuters) - U.S. Republican presidential nominee Donald Trump named 64 agriculture policy advisors on Tuesday, including the governors of Iowa and five other farm states and a former federal agriculture secretary.

The announcement came as Trump, a New York businessman seeking his first elected office, looks to improve his standing among voters, particularly those in swing states such as Iowa, where some recent opinion polls show Trump and Democratic nominee Hillary Clinton in a tight race.

Republican Governors Terry Branstad of Iowa, Sam Brownback of Kansas, Jack Dalrymple of North Dakota, Dennis Daugaard of South Dakota, Mary Fallin of Oklahoma and Pete Ricketts of Nebraska were included on a list of advisors distributed by Trump's campaign.

Branstad spokesman Ben Hammes said in an interview that the governor will focus on increasing government support for renewable energy as part of the committee.

Also on the list were John Block, U.S. agriculture secretary under Republican President Ronald Reagan from 1981 to 1986, and former Governors Rick Perry of Texas and Jim Gilmore of Virginia, who both unsuccessfully ran against Trump for the Republican nomination.

“The members of my agricultural advisory committee represent the best that America can offer to help serve agricultural communities," Trump said in a statement.

Members of an executive board will "convene on a regular basis," he said.

Committee members have already talked via telephone to outline some of the issues they expect to tackle, committee member A.G. Kawamura said in an interview.

They range from immigration and climate change to global trade and "how to define food and energy security for the U.S. in the years ahead," said Kawamura, a former California agriculture secretary.

Battles between the agriculture sector and its critics have grown fierce in recent years - from fights over water access in California and declining grain prices, to mounting pressure from consumer groups over how food is produced and labeled.

Both presidential campaigns have largely ignored the sector, though, Kawamura said, adding that lack of discussion was one of the reasons he joined Trump's committee.

In June, representatives of about a dozen agricultural associations, including the American Farm Bureau Federation and the National Farmers Union, met with staffers for Democratic candidate Hillary Clinton for the first time to begin a discussion on farm policy.

Clinton had a 6-percentage-point lead over Trump in a Reuters/Ipsos tracking poll released on Tuesday.

(Reporting By P.J. Huffstutter and Tom Polansek; Editing by Jonathan Oatis)