Jesse Benton, the GOP political strategist spearheading Senate Minority Leader Mitch McConnell’s reelection bid, resigned from his post Friday amid a federal investigation involving a 2012 presidential campaign he ran.

Benton said in a statement that there had been “inaccurate press accounts and unsubstantiated media rumors about me and my role in past campaigns that are politically motivated, unfair and, most importantly, untrue.”

“What is most troubling to me is that they risk unfairly undermining and becoming a distraction to this reelection campaign,” he wrote.

Benton said that “with a heavy heart” he offered his resignation to McConnell (R-Ky.), who “reluctantly accepted.” His decision to leave the campaign was first reported by the Lexington Herald-Leader.

The resignation came two days after former Iowa state senator Kent Sorenson pleaded guilty to two federal charges, admitting that he accepted thousands of dollars in concealed payments from the 2012 presidential campaigns of Rep. Michele Bachmann (R-Minn.) and former congressman Ron Paul (R-Tex.) to secure his endorsement.

Sorenson pleaded guilty to one count of causing a federal campaign committee to falsely report its expenditures and one count of obstruction of justice.

A Justice Department spokesman confirmed this week that the investigation into the payments made to Sorenson is ongoing.

Benton is married to Paul’s granddaughter and served as chairman of the former congressman’s 2012 presidential campaign. It is unclear if he knew about payments made to Sorenson, but e-mails published last year indicate he was involved in efforts to get him to defect from the Bachmann campaign.

A top Paul campaign official, Dimitri Kesari, was involved in efforts to pay Sorenson for his support, according to a report by a state-appointed independent counsel. At one point, Kesari gave Sorenson’s wife a check for $25,000 during a meeting at an Altoona, Iowa, restaurant.

David A. Warrington, who served as general counsel to Paul’s 2012 presidential campaign, did not respond to requests for comment this week.

Paul’s campaign committee doled out $80,000 in legal fees this spring — nearly twice as much as it spent on legal costs in all of 2013, according to federal campaign finance reports.

Benton’s departure is a blow to McConnell, who is in a tough reelection fight against Democratic challenger Alison Lundergan Grimes. “Senator McConnell owes the people of Kentucky a full account of what he knew and when he knew it,” Grimes spokeswoman Charly Norton said.

When he originally tapped Benton, a longtime Paul operative, it was seen as a savvy way to bolster his standing with tea party and libertarian voters. The partnership was also expected to boost a 2016 White House bid by Sen. Rand Paul (R), the junior Kentucky senator and son of Ron Paul.

In a recorded phone call posted online last year, Benton described working for McConnell as “holdin’ my nose for two years because what we’re doing here is going to be a big benefit to Rand in ’16.” Benton and McConnell later joked about the remarks.