Soaring diesel prices taking a toll on Oklahoma rancher

"It's probably the most stressful time in my life," Scott Belden told ABC News.

In Broken Arrow, Oklahoma, third-generation rancher Scott Belden is in the middle of harvest. And anxious.

It's not just the demanding time of year that has the lifelong rancher uneasy -- the record-breaking cost of diesel is also putting additional pressure on him and his business.

"The inputs are out of control. The diesel prices are out of control, along with everything else. So we're just in a very trying time. Very uncertain," he said.

Oil prices have spiked since the start of the Iran war. The average price for a gallon of diesel was $6.32 on Thursday, according to AAA, and prices have increased by more than 65% since the war began back in February.

Belden says he wakes up at 3 a.m., worrying about how to make it all work with the crushing fuel costs hitting his bottom line. All his vehicles and equipment run on diesel, and during harvest, he burns 90 to 100 gallons of the fuel a day.

Belden's ranch includes cattle and custom harvesting for hay -- the latter he says is "absolutely unprofitable" with the costs of fuel.

"If I want to continue to operate, I'm going to buy diesel. No matter what the price is, I'm going to buy diesel," he said.

"It don't take no [mathematician] to figure out that it's costing me $1,000 to $1,400 more a week," he said.

"It's a very trying time when you know, you don't know when that's going to end. You don't know, and you can't -- you can't always pass that on to your customers because you set the prices, and they're all -- they're all struggling, too. You know everybody's in this together," he added.

With the midterm elections less than three weeks away, polling shows the economy and cost of living are a top concern for many voters.

A three-time Donald Trump voter, Belden believes Republicans will pay the price for the ongoing pain at the pump.

"Middle of America is hurting," Belden warned. "The lifeblood of America is diesel fuel. Everything you eat, consume, wear is delivered with a diesel-powered vehicle. So, I do believe it's going to hurt them tremendously."

While Belden stands by his vote for the president, he is glad Trump is term-limited.