Dominion’s C.E.O. defends his firm’s voting machines to Michigan lawmakers, denouncing a ‘reckless disinformation campaign.’

A day after Michigan’s 16 electoral votes formally went to President-elect Joseph R. Biden Jr., a voting machine manufacturer told state senators that he stood by his company’s work, and shot down unfounded allegations that the results may have been manipulated.

Dominion Voting Systems is the victim of “a dangerous and reckless disinformation campaign aimed at sowing doubt and confusion over the 2020 presidential election,” John Poulos, the company’s chief executive, told the State Senate Oversight Committee.

The company has come under fire from supporters and lawyers for President Trump, who have claimed without evidence that the company’s voting machines switched votes from Mr. Trump to Mr. Biden.

Mr. Poulos assured the committee that his company had no connections to House Speaker Nancy Pelosi, the former Democratic presidential nominee Hillary Clinton, or George Soros, the billionaire financier who is a subject of conspiracy theories on the right.

“The comments about our company being started in Venezuela with Cuban money with the intent to steal elections are beyond bizarre and are complete lies,” Mr. Poulos added. “My company started in my basement, which happened to be in Toronto.”

State Senators, who are conducting an investigation into alleged reports of irregularities in the 2020 election, continually returned to tiny Antrim County in northern Michigan, where human error in the local clerk’s office related to updating the software in some vote tabulators caused votes for Mr. Trump to be inadvertently counted for Mr. Biden. The mistake was caught and corrected before the results of the vote were certified. Supporters of Mr. Trump have pointed to the error as proof of widespread fraud in the election.

“If all of the tabulators had been updated per our procedure, there wouldn’t have been any error in the unofficial report,” Mr. Poulos said. “Human mistakes happen, especially in busy election years when election officials work tirelessly through weekends and holidays for months on end.”

He dismissed as seriously flawed a report from a self-proclaimed election fraud expert on the Antrim County situation that has been cited by Trump allies.

Lawmakers also repeatedly asked about various other unfounded allegations, including that Dominion tabulators were connected to the internet, and consequently susceptible to hacking; and that the machines employed ranked-choice voting in Michigan.

“Would it be impossible for anything to be manipulated,” asked State Senator Michael MacDonald, a Republican.

“I don’t think so, but if it was possible, it would certainly be detectable,” Mr. Poulos responded, pointing to Michigan’s use of paper ballots. “If there was any manipulation of the system, those paper ballots would not match the machine totals.”

Although there is nothing the committee can do to alter the results, it plans to continue to investigate the election, with plans to subpoena the city clerks of Detroit and Livonia, two cities in Wayne County that drew national attention last month after Republicans on the county’s board of canvassers initially opposed certifying the election results because of minor irregularities.