You might call Harold Hamm the Donald Trump of the oil patch.

The Oklahoma oilman will take the stage at the Republican National Convention for a prime-time speaking slot on Wednesday, and, like Trump, he brings a flair for showmanship in business and a history of messy divorce proceedings. The bond between Hamm and Trump, both 70 years old, has given the Continental Resources CEO outsize influence on the energy policy of the GOP presidential nominee — leverage that might propel him all the way into the Cabinet next year.

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"Harold is very influential," said one oil industry lobbyist with close ties to Hamm, who asked for anonymity to discuss his relationship to the Trump campaign.

While Rep. Kevin Cramer (R-N.D.) drafted a series of energy policy recommendations for Trump and operates as something of a campaign surrogate, his pull with the Manhattan real estate mogul is limited. "It’s not Kevin Cramer; it’s Harold. It’s always been Harold," the lobbyist said.

Hamm heavily influenced Trump's May speech to an oil industry conference in Bismarck, North Dakota — one of only a handful of policy addresses given by the candidate — and he helped coordinate a June meeting of business leaders and lobbyists in New York dubbed the Trump Leadership Council. Hamm has also sought to build support for Trump within the oil industry, where some players have long harbored fears that Trump is an energy policy neophyte.

And so far, the two billionaires are in lock step on energy issues. Hamm, like Trump, has long called for rapidly expanding U.S. oil and gas development to curb the power of oil-rich OPEC nations, and they've both criticized President Barack Obama and Hillary Clinton for emphasizing renewable energy over fossil fuels.

"I’m worried about our country. I’m worried about the direction it’s going," Hamm said in an interview, blasting Democrats for "choosing to do away with all fossil fuels. That would put us right back into OPEC’s grasp." He added, "We’re funding Islamic terrorism by buying oil from those countries."

To hear Hamm tell it, Trump has long shown an interest in energy issues. After crossing paths at events in New York City, Trump invited Hamm to Trump Tower about four years ago for their first face-to-face meeting, Hamm told POLITICO.

The New Yorker peppered him with questions about how technologies like horizontal drilling helped his company revolutionize oil and gas development in North Dakota. Hamm said they developed a friendship and regularly kept in touch even before Trump decided to run for president.

During one visit, Trump gave Hamm some of his branded ties. Hamm wore one for a photo that appeared on the cover of a business magazine. Trump was so delighted, Hamm said, that he sent over more ties.

Hamm played a similar role for Mitt Romney in 2012, formally signing on as an energy adviser to the former GOP nominee two months before the ex-Massachusetts governor clinched the nomination. He also gave $985,000 to a super PAC supporting Romney early in 2012 and left the door open to serve in Romney’s administration, just as he has this year with Trump.

Trump’s dependence on the oil CEO for energy counsel is "not surprising to me," another oil industry lobbyist said, "because that's what you know to do — call Harold Hamm. Does [Hamm] know anything outside of drilling for oil? No. Does the Trump campaign care? Probably not."

Hamm says he isn't working directly for the campaign right now, and he's just offering Trump his advice in an informal way. Federal Election Commission disclosures show he hasn't made any contributions to Trump’s campaign or super PAC. But Hamm attended a Monday reception in Cleveland for the pro-Trump Great America PAC, suggesting that his pocketbook soon could open.

Hamm was coy about whether he'll start pouring his cash into Trump's campaign or the super PAC supporting him. "I’m convinced that we have to change the course that America’s on," he said. "As to how that will materialize in financial support, I just can’t say yet.”

Still, Trump’s campaign did not rule out giving Hamm a prominent spot on the team, before or after Election Day.

"Mr. Hamm is a person Mr. Trump has great respect for and is an expert on energy,” Trump spokeswoman Hope Hicks said when asked about Hamm’s future on the campaign or in a Republican administration. “We are excited to have him speak at the convention and thankful for his support."

His close ties to Trump have sparked furious speculation among Republicans and oil industry heavyweights that Hamm could be tapped as energy or interior secretary if the GOP nominee defeats Clinton.

"He’s probably got better than 50-50 odds of being the energy secretary in a Trump administration. That would be my guess. I think he’d be a natural choice," said GOP donor and Trump backer Dan Eberhart, the CEO of the oilfield services company Canary LLC.

Still, some of Hamm's longtime allies in Oklahoma doubt he'd depart from his home state.

“I never got that indication, that he’s interested in going to Washington,” said Triad Energy co-owner Mike McDonald, who has known Hamm for 35 years and serves as president of the Hamm-chaired Domestic Energy Producers Alliance. “He’s just doing this for the good of the country.”

Hamm didn't rule out the possibility of serving in a Trump administration, though he insisted he has no designs on such a role.

"Obviously, I have a pretty full-time job," he said. "But I’d be honored to be asked. I’d have to see what develops there."

Hamm is hardly alone among oilmen in limiting his financial commitment in the presidential campaign this election cycle, though he has given $30,000 to the National Republican Congressional Committee and $15,000 to the Republican National Committee, according to FEC records. He grabbed headlines last year by settling acrimonious divorce proceedings with ex-wife Sue Ann with a personal check for $975 million — more than 30 times the $25 million that Trump reportedly agreed to settle for with ex-wife Ivana in 1991.

Unlike four years ago, when oil prices were soaring, the industry is limping through a prolonged downturn that has battered even the biggest companies, which could account for the dearth of contributions to Trump from the industry.

Still, some of Hamm's singular influence on Trump is also a function of lingering skepticism about the nominee-in-waiting among other oil and gas executives, even as they cringe at the prospect of a President Hillary Clinton tilting further to the left on the environment.

“Nothing against either candidate, but we all wish there were better candidates on each side,” Pioneer Natural Resources CEO Scott Sheffield said Tuesday at the Center for Strategic and International Studies.

Hamm wouldn't reveal much about his Wednesday night convention speech, his first remarks at a political convention. But he indicated he planned to focus on national security and jobs. He employed both of those themes during the fierce lobbying battle to repeal the four-decade-old ban on exporting U.S. oil, which ended with an industry victory in December when Congress agreed to open the flow of U.S. oil to other countries as part of a bipartisan budget deal.

Williams & Jensen lobbyist George Baker, who worked on the same side as Hamm — although not for him — to repeal crude export restrictions, praised him for his dedication to the cause.

“I know he worked very hard, and the guys who represented him worked very hard, to make sure he got around and tried to educate the Hill, educate others,” Baker recalled.

Using his oil producers group as a megaphone, Hamm delivered a protectionist case for unrestricted oil exports, accusing foreign-owned refiners in the U.S. of favoring heavier foreign crude over the lighter U.S. shale oil. That might not be out of place in a Trump campaign that has blasted trade deals and called for the U.S. to get "a piece of the profits" from the proposed Keystone XL pipeline.

"He has long been a leader in increasing domestic production and getting off imported oil and policies that encourage the U.S. to invest more in foreign production than we do in U.S. production," said Denise Bode, a former Oklahoma energy regulator and oil industry lobbyist who has known Hamm for decades. "He’s very much, I would say, a populist in that respect."