CONCORD, N.H. — New Hampshire Democrats are alleging Republican gubernatorial candidate Chris Sununu may have cast improper votes related to clients represented by his brothers’ lobbying and public affairs business.

At a press conference Wednesday, the Democratic Party pointed to an instance when Sununu voted as an executive councilor on a contract with a company his brothers’ firm represented. It offered no other evidence, but called for disclosure of a client list for Sununu’s brothers’ firm, Profile Strategy Group.

Sununu’s campaign called the press conference a “cheap political attack” and denied wrongdoing.

“Chris Sununu has been open and transparent during his tenure on the Executive Council about any conflicts of interests that have come before him,” spokesman Dave Abrams said. “He is always willing to recuse himself in instances of conflict, and any claim to the contrary is patently false and motivated purely by partisan politics.”

Sununu is running against Democrat Colin Van Ostern, a fellow executive councilor, to replace outgoing Democratic Gov. Maggie Hassan. The Executive Council is a five-member body that votes on large state contracts and gubernatorial appointments.

In 2013, the council took up a contract for inmate telephone services in state correctional facilities. Two companies were involved: Securas Technologies and Inmate Calling Solutions. Securus Technologies won the contract unanimously in 2012, but it was later canceled and rebid after the state found it needed to re-write part of its initial contract request, according to the contract. When it was rebid in 2013, Inmate Calling Solutions won the contract.

Minutes show Sununu expressed concern that Securus was getting “railroaded” out of the contract. After an initial delay, Sununu did vote to award the contract to Inmate Calling Solution.

At the time, a partner in Profile Strategy Group, Jamie Burnett, was listed as a lobbyist for Securus. Michael Sununu, Chris’s brother, had been registered as a lobbyist for Securus in 2012. Now, the Democrats are calling on Profile Strategy Group to release all of its clients.

“Should Chris Sununu be elected governor, he would be directly involved with contracts and issues involving Profile Strategy Group clients,” said Paul Hodes, a former Democratic congressman.

Burnett said Profile Strategy Group has always disclosed its lobbying clients as required.

“As can be determined through the required lobbying disclosure, Profile Strategy Group has done very little lobbying,” Burnett said in an email. “What lobbying the firm has done has been properly disclosed, and (Democrats) know this. This is just politics.”

Van Ostern, for his part, served on the council while his wife, Kristyn Van Ostern, worked as the chief financial officer for the Community College System of New Hampshire. The council has voted on contracts related to the system. Kristyn Van Ostern left the job earlier this year.

“Unlike the Sununu family’s hidden conflicts, Colin routinely recused himself from appointments to the community college system board who worked with his wife in her past role,” spokesman Matt Trojan said.

This story has been corrected to show the name of the company that initially won the contract is Securus, not Securas.