WASHINGTON » The top Democrat on a House committee launched an inquiry Monday into a consulting firm under scrutiny for voter-registration irregularities, seeking details about its relationship with the Republican National Committee.

In a letter, Rep. Elijah E. Cummings of Maryland asked Nathan Sproul, who runs Strategic Allied Consulting, to make himself available for an interview by Oct. 12, and to provide copies of his correspondence with the RNC and state political parties. Cummings is the ranking Democrat on the Oversight and Government Reform Committee.

State officials in Florida are investigating voter registration activity by Strategic Allied, which was hired by the RNC this summer to do get-out-the-vote work in seven swing states.

The national party directed at least $3.1 million through state parties to Strategic Allied before severing ties with the company last week after election officials in Florida’s Palm Beach County discovered potentially fraudulent voter registration forms submitted by one of its workers. Since then, 10 other Florida counties have reported suspicious voter registration applications that trace back to the state Republican Party.

Officials in Colorado, Nevada and North Carolina are also investigating isolated reports of registration irregularities linked to Strategic Allied.

In a statement posted Monday on Strategic Allied’s website, the company said it “has never tolerated even minimal violations of election law when registering voters” while the firm and its affiliates registered about 500,000 voters in 40 states in the last eight years. “It would surprise me if there were no problems,” said Mark Leibowitz, a spokesman for Sproul.

“Inevitably, there have been accusations of ‘bad registrations,’ isolated instances that have been thoroughly investigated not only internally but by the appropriate legal authorities,” the firm said in its statement. “In every instance, our company and its affiliates have been cleared of any wrongdoing.”

Sproul, a former head of the Arizona Republican Party, said last week that, because of bad publicity from past investigations, the Republican National Committee requested that he set up a new firm to handle the work this year so the RNC would not be linked to the allegations. RNC spokesman Sean Spicer disputed that contention.

Sproul does not appear on the corporate paperwork for Strategic Allied.

Democrats have seized on the investigations into Strategic Allied’s work, noting that the GOP has raised the alarm about the risk of voter fraud as it has pushed to tighten voter identification requirements.

Rep. Ted Deutch, D-Fla., released a letter Monday to Republican Gov. Rick Scott asking him to appoint a bipartisan task force to investigate. “We have a governor who has led this crusade against illusionary voter fraud for months in an effort to suppress the vote and kick eligible voters off the rolls,” Deutch said. “Now when he’s confronted with real voter fraud with major implications on the outcome of this election, he’s missing in action.”

In a statement, Scott noted that the company has been fired and its forms turned over to law enforcement: “We have zero tolerance for any illegal voting activity in Florida.”

Florida elections officials have identified dozens of suspicious forms turned in by the state Republican Party.

In Miami-Dade County, three forms with similar handwriting were also turned in by a voter registration effort run by the National Council of La Raza. “We’re really trying to get to bottom of the complaint so we can address it,” said Camila Gallardo, a spokeswoman for the advocacy group.

Those applications, like the ones tied to the GOP program, were turned over to the Florida Department of Law Enforcement, said Chris Cate, spokesman for the Florida Division of Elections.

Officials in other states also are investigating.

In North Carolina, state elections officials are investigating a handful of suspicious voter registration forms submitted by Strategic Allied in Mecklenburg County, the state’s largest county, according to the director of the county elections board. The county also turned over one irregular form that came in from Organizing for America, an arm of the Democratic National Committee.

The Nevada Secretary of State’s office is investigating a complaint filed by a Democrat who said she saw a Strategic Allied employee direct a woman who had registered as a Democrat to tear up that form and fill out one that did not list a party affiliation.

And in Colorado, a district attorney’s office is looking into a report by an attorney for Strategic Allied that one of its employees had torn up a completed voter registration form.