The Republican US senator Roger Marshall says he has finally paid off a bakery debt – after six years and repeated collection attempts reported by a Kansas business that had supplied a large order of treats for a 2020 election watch party.

“We have absolutely no idea how this happened”, the Kansas senator wrote in a social media post containing a screenshot of the payment on a $678.75 invoice from Holly’s Sweet Treats as well as his $1,300 payment. “And we have repaid the bill … double.”

Word of Marshall’s cookie debt became widely known after an 8 October social media post from Holly Thomas, a baker from Hutchinson, Kansas, which began: “Do you know why I will never vote for Roger Marshall?”

The Holly’s Sweet Treats proprietor recounted how Marshall’s campaign had “ordered cookies and treats from my bakery” for a 2020 primary election watch party that preceded his winning his first six-year Senate term.

“For nearly a year,” the post continued, “I made repeated attempts to collect payment, reaching out by phone and email. I never received a return phone call, and the invoice was never paid.”

Thomas said that unpaid invoice was particularly challenging because it was during the Covid-19 pandemic, “when small businesses everywhere were struggling just to keep their doors open”.

“Every single dollar mattered,” Thomas wrote. “Those cookies and treats cost money to make, employees’ time to prepare, and resources that my little business couldn’t afford to give away.”

Roger Marshall and his wife, Laina, thank supporters for a win at an election watch party in Topeka, Kansas, on 3 November 2020. Photograph: Orlin Wagner/AP

Thomas concluded: “Six years later, I haven’t forgotten. This isn’t about political parties or policy disagreements. It’s about my personal experience as a small business owner and the importance of honoring financial commitments.

“That experience is why Roger Marshall will never get my vote.”

Thomas’s post achieved internet virality and unsurprisingly caught the attention of Marshall’s camp.

By Saturday, Marshall had published his own social media post addressing Thomas’s statement, saying on X: “As some folks may have seen, there was a post on social media regarding an unpaid 2020 cookie bill.

“We have absolutely no idea how this happened, but rest assured as soon as it became known to us, we immediately attempted to contact the business in order to apologize, and we have repaid the bill from 2020, double.”

Marshall’s post – along with the picture of the paid invoice to Holly’s Sweet Treats – quickly drew a community note from X users aiming to provide what the platform characterized as additional context.

“Multiple attempts to get paid were ignored,” the community note said, linking to Thomas’s Facebook post.

Many users gave Marshall what they considered his just desserts in the form of harsh comments, with one commenter saying: “You got caught, and that’s the only reason you paid.”

Others calculated that he actually owed Thomas more than $1,400 at 18% simple annual interest for six years. And one noted that $678.75 doubled is $1,357.50 – not $1,300.

Thomas on Saturday published another Facebook post that acknowledged Marshall’s having “paid his bill”.

“Better later than never, right?” Thomas wrote. “Six years later, I guess we can finally mark that invoice PAID!”

Marshall’s response to Thomas’ publicizing his late payment unfolded in a political climate which has the Democrats favored to win control of the US House during the 3 November midterms.

Polls more recently have shown that the Democrats also have a relatively viable chance to win US Senate seats in states that traditionally elect Republicans and possibly gain a majority in that chamber, too – given Donald Trump’s unpopularity amid high living costs and the war in Iran that the president helped start alongside Israel.

Marshall’s announcement about paying Thomas also arrived after the Cook Political Report amended its prediction for his November re-election run against Democratic challenger Adam Hamilton from leaning in the Republican’s favor to being considered a toss-up.

The announcement from Marshall – a physician – about the tardily settled bill also came after the New York Times reported in September that his obstetrics-gynecology practice had sued hundreds of patients over the years in connection with unpaid medical bills, including for as little as $101.