“I personally don’t know anybody that’s against this,” said Richard Le Jeune, who raises 200 cattle on his 573-acre property in the tiny hamlet of Halfway, Mo., 30 miles north of Springfield. “Some of these city people don’t have a clue what goes on in the country and how food is produced. We need this to keep the outsiders from trying to run things.”

While watching Fox News from his living room on Wednesday, Mr. Le Jeune interrupted himself to nod at the television when a commercial advising viewers to vote against the amendment came on. “This is the second time in two days I’ve seen this one,” he said.

Other farmers said the amendment, which is brief and vaguely worded, would permanently enshrine a special status for ranchers and farmers in the Constitution. Darvin Bentlage, who raises cattle and grows soybeans, corn and wheat in Golden City, Mo., said the people who were pushing the amendment “don’t know what kind of can of worms is going to open up.”

“One thing’s for sure — it’s going to put ag culture above everybody else,” he said. “We’re going to be a different class of people. You won’t be able to complain about anything that we do. That should never be the case.”

Agricultural groups representing cattle, soybean and corn farmers have lined up in favor of the amendment, while the editorial boards of nearly every major newspaper across the state have sounded off against it. The Kansas City Star editorial board called it an “unnecessary and potentially harmful proposal” and “a concerted effort to shield factory farms and concentrated agricultural feeding operations from regulations to protect livestock, consumers and the environment.”

“It’s the agricultural establishment trying to build a firewall against growing consumer concerns,” said John E. Ikerd, professor emeritus of agricultural economics at the University of Missouri in Columbia, likening it to early regulation of tobacco. “If we’d had a ‘right to smoke’ amendment at that time, we’d still have smoke-filled offices and airplanes.”