Boris Johnson's fiancée, Carrie Symonds' role in Downing Street has been questioned, and a conservative think tank are demanding an inquiry into how much influence she actually has.
The Bow Group said No 10 need to clarify her position after reports in the media suggest that she was "taking a central role in running the country".
The group has also asked for details of any meetings she has attended or demands given to special advisors and civil servants.
Ben Harris-Quinney, chairman of the Bow Group, said Ms Symonds has not been elected, appointed and holds no legal or constitutional powers to make decisions relating to who should hold government posts, to be party to privileged information, or to set the policy direction of the country
Ms Symonds used to be the Conservative Party's head of communications, but no longer holds an official role.
Speaking on Monday, the PM's press secretary Allegra Stratton added: "The prime minister's fiancée is on maternity leave, she's raising their son Wilf."
She said Ms Symonds would shortly begin her new role as head of communications at wildlife charity the Aspinall Foundation.
Harris-Quinney added: "Failure to clarify Ms Symonds' position and authority, and to ensure that Ms Symonds is not and cannot take any action in governing the United Kingdom, potentially has huge hazards for the government, the Conservative Party, and the nation."
He said that the public take a very dim view of cronyism. Stating further that democracy in Britain is and must always be sacred, and no one should be involved in running the country without accountability to the people.
Ms Symonds' first job in politics was working for the then-Tory MP and now peer, Lord Zac Goldsmith.
In 2010, she began working as a press officer for the Conservative Party and two years later worked on Mr Johnson's successful campaign to be re-elected mayor in London.
After rising through the ranks, she left her role as head of communications for the party in 2018, and the next year she was linked with Mr Johnson romantically.
Conservative MP Laura Trott told the BBC that briefings against the prime minister's fiancée are "distasteful".
"I used to work with Carrie, she's an incredibly talented and able person and I think there should be some consideration given about whether some of these things would be said about a man," she added.
Samantha Cameron, has also recently said the suggestion Ms Symonds has undue influence over her partner is "sexist and demeaning".