U.S. Sen. Rand Paul (R-Ky.) and his father, former congressman and 2012 presidential candidate Ron Paul. (Alex Wong/GETTY IMAGES)

In defeat, Kent Sorenson no longer looked like a man worth bribing. He cut a burly figure, hulking behind the witness stand, but he spoke in a soft voice — about how pathetic his "time in politics" was as a fast-rising Republican state senator.

As he told a jury about leaving former representative Michele Bachmann’s presidential campaign to work for Ron Paul’s, Sorenson described days of stress and panic culminating in an office huddle about how to deny to reporters that he’d been promised $8,000 per month to switch.

Sorenson was not on trial this week in federal court in Des Moines; he had already pleaded guilty to receiving payments and then lying about them. Instead, he was testifying against Dimitri ­Kesari, Paul’s 2012 deputy campaign manager, and Jesse Benton, Paul’s campaign chairman. In a trial expected to last at least through next week, Benton — who is married to Paul’s granddaughter — faces one charge and Kesari faces five related to the scheme.

“Dimitri took my phone that night,” Sorenson told the jury. “I was a rat, and he knew it.”

The trial offers a rare glimpse into the world of politics as it is widely practiced — and rarely prosecuted. The case had ensnared Paul, a former congressman from Texas who had been seen as so incorruptible that he bragged that lobbyists didn’t bother to call him. It had burned the congressman’s son, presidential aspirant Sen. Rand Paul (R-Ky.); the indictment of Kesari and Benton dropped the day before the first 2016 GOP debate.

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Federal prosecutors said at the outset of the trial that neither of the Pauls was to blame.

“Ron Paul knew nothing about the coverup,” government attorney Richard Pilger said at the trial’s outset. “Ron Paul wanted his campaign to be about ideas.”

Before Sorenson’s testimony, a jury had seen page after page of e-mails confirming that the former state senator had asked for a payoff, that he had gotten it and that the people who were supposed to be winning the Iowa caucuses for Paul had concocted a scheme to cover it up.

Sorenson testified that Kesari reached out to him in early 2011, but the state senator endorsed Bachmann for president. On the stand, he said the Minnesota congresswoman paid him $7,500 per month to chair her Iowa campaign. As she faded, he realized that she "had no business being president" and that he would caucus for Ron Paul even if he remained her state campaign chairman.

Kesari tested his loyalty, and Sorenson mulled a switch. On Oct. 29, 2011, an emissary sent the a Paul campaign official a three-page PDF of demands. Among them: Matching “his current salary of $8,000, even after MB drops out of the race, for the majority of 2012.” The figure was a lie — Sorenson made less. The e-mail also suggested dropping $100,000 in Sorenson’s new PAC.

This began a series of e-mails that could have ended or exposed the scam. "It appeared that you were trying to sell Kent's endorsement for hundreds of thousands of dollars," Benton wrote to the emissary, Aaron Dorr. Paul's campaign, Benton said, "would never engage in such dealings."

But as e-mail revealed, the sides kept up their flirtations for months. Unbeknownst to Paul, ­Kesari kept checking on Sor­enson. Finally, on the day after Christmas 2011, Sorenson and his wife met Kesari at a steak house and got serious.

“I remember us joking about which campaign would pay for dinner,” said Sorenson. “We were having such financial difficulties, so we were laughing about it.”

Kesari picked up the check, then slipped Sorenson’s wife another check — $25,000, drawn from a jewelry company run by Kesari’s wife.

Sorenson went to one more Bachmann campaign rally, then felt hurt that the campaign — which knew he had considered bolting for cash — didn't let him speak. He took the campaign manager for a drive, told him "I was sorry for what I was about to do," then drove to a Ron Paul rally to endorse his new candidate.

"I asked, 'Will you take care of me?' " Sorenson remembered. "Jesse said, 'You're bleeding for us, we'll take care of you.'"

E-mails produced by the government indicate Sorenson's dithering and demands almost blew the deal.

"Kent is getting cold feet," Kesari told Benton and John Tate, Paul's campaign manager, the day before Sorenson's switch. "Damn, I was afraid of this."

In court, Benton was emotionless when another e-mail was read: "Either he honors his commitment, or we expose him as the money-grubbing shakedown artist that he is."

Sorenson flipped. Bachmann went on national TV to say that her chairman had been bought.

That led to the media strategy to lie about what happened. On Dec. 28, 2011, the day of the switch, Benton told The Washington Post and other outlets that Sorenson was not being paid. Since he had never cashed the $25,000 check, the campaign came up with a solution: Just delay the first payment it had planned to wire him.

“Hold for a couple of days,” Benton told the campaign’s compliance director, Fernando Cortez-Mira.

“We are holding until after the filing,” Kesari wrote in an e-mail. “I don’t want it showing up in this quarter’s filings.”

“Wipe it off the books,” Tate wrote.

It stayed off the books. Kesari cut a deal with ICT, a Maryland company, under which the company would cut fake “invoices” for “production” work, and the money would be wired to Sorenson. An embarrassing but legal act was turned into a wild scheme involving a pass-through company — a scheme that campaign treasurer Lori Pyeatt, Paul’s daughter and Benton’s mother-in-law, knew nothing about.

In 2013, a disgruntled former campaign staffer, Dennis Fusaro, started releasing documents and surreptitiously recorded audio about the inner workings of the campaign. His revelations started an Iowa ethics investigation of Sorenson. As the investigation built, Cortez-Mira compiled fishy invoices and sent them to Benton as evidence and a warning: “Dennis is not a good guy,” Cortez-Mira wrote. “But then neither is Dimitri IMO.”

According to the government, Benton took all of that information and misled the FBI agents who interviewed him. A lengthy cross-examination of one of the agents, Karen LoStracco, revealed that Benton had denied knowledge of any kind of deal with Sorenson.

Meena Sinfelt, one of Benton’s attorneys, asked jury members to remember “what you paid on your taxes two years ago,” suggesting that a busy campaign chairman could hardly remember the details of some endorsement deal.

Kesari, who had swapped out his trademark bow ties for a bland business ties for the trial, endeavored to look like an innocent operative betrayed by a corrupt state senator. Sorenson, said attorney Jesse Binnall, "decided to use the $25,000 check as leverage." It was the senator, not Kesari, who turned a simple endorsement deal into extortion, Binnall said.

Paul himself may have been the campaign operatives’ best witness. He struggled to read the documents he was handed. He hardly cared who Sorenson was. “We probably crossed paths,” he shrugged, recounting how useless his endorsement had been.

And he could not be angry at Benton for the sins of Sorenson or the prosecutors who flipped him. “As far as I’m concerned,” Paul said, smiling at his grandson-in-law, “nothing has changed.”

Benton and Kesari each face up to five years in federal prison for each count. Sorenson faces up to 25 years.