Thune said the office would provide little help for farmers who already deal with plenty of red tape. They don't need another layer of government, said Thune, a former three-term congressman.
"The reason we have some of the problems that we have today in agriculture is because we have too much bureaucracy ... I'm not for more of that I'm for less of that."
Instead, "more control at the local level will get a better outcome," he said.
In defending the plan, Daschle, the Democratic leader of the U.S. Senate, said the office could provide advocacy services for farmers. Funding could be dedicated to helping small farmers and the staff could be carved from existing resources, he said.
"For my money, that means ... an effort that ensures that farmers and ranchers at long last have a voice in Washington like they've needed in a long, long time," Daschle said.
Thune said more employees in Washington won't provide any assurance that farmers will be heard and called the plan "an election year thing."
Being an advocate for farm issues is a job of elected officials, said Thune. "That's what you're there for Tom," he said.
The hour-long debate — the first in South Dakota's high-profile Senate race — came during Dakotafest, a farm expo near Mitchell. At times it sounded more like a college football game than a political event as the audience cheered and occasionally launched a verbal attack or shouted out praise.
One of the liveliest exchanges came after a question about drought relief.
Thune said drought relief didn't come to South Dakota until after Daschle lost his position as Senate majority leader in the 2002 elections.
The measure only passed then because "people sat down and said `what can we do to get this done,"' said Thune. If people had been willing to discuss a solution before it became a political issue, assistance could have come a lot sooner, he said.
"I can understand why John feels awfully defensive about drought assistance," Daschle responded. Thune was not able to persuade President Bush to go along with drought aid during his unsuccessful U.S. Senate bid in 2002, the Democrat said.
The record is clear on which candidate has fought for drought relief, he added.
Daschle said in 1998 he asked former President Bill Clinton to veto a drought appropriations bill because it didn't contain enough money. Clinton listened, vetoed the bill "and we got six billion dollars in disaster assistance," said Daschle.
Farmers and ranchers don't need more loans — they need meaningful help, Daschle said.
Philip Mathews of Draper said he enjoyed the debate and thought the rhetoric was fiery at times. "They got a little testy with each other," said Mathews, who added that his views are more in tune with Thune.
"It's time for Tom Daschle to go," he said.
Trecia Rickenbach of Sioux Falls said Daschle is not an impediment to South Dakota's interests in the Senate, as Thune espouses. And Daschle got the best of Thune in the debate, she said.
"I felt that Thune was very defensive and argumentative," Rickenbach said.
Questions from audience members were funneled to the panel of reporters. The questions were supposed to be limited to agriculture, but many were about issues such as abortion and same-sex marriage.
One person who offered a question didn't seem impressed with either candidate. The question: "I wonder if these two and all politicians would agree to lie detector tests."