Downing Street has cast doubt on a reported move by Labour to nominate John Bercow for a peerage.
“It is a long-standing convention that leaders of the opposition can nominate individuals representing their party for peerages,” they said.
Downing Street has declined to comment on specific nominations, while it is understood that no list of potential peers from Jeremy Corbyn has been submitted to Mr Johnson.
Labour has declined to comment, but has not denied the reports.
The reported move has raised eyebrows at Westminster given Mr Bercow had been a Conservative MP prior to taking up the role of parliamentary referee.
Mr Bercow entered parliament as MP for Buckingham in 1997, before becoming Speaker in 2009.
He stepped down from the role, which involves presiding over proceedings in the Commons, in November.
Mr Bercow was seen as a champion of backbench MPs and their efforts to hold the government to account, particularly on Brexit.
But critics frequently accused him of straying out of the bounds of his authority and raised questions about his impartiality over a number of rulings which were considered to favour Remain supporters.
He survived numerous attempts to remove him from the chair, as well as revelations about his expenses and allegations of bullying, which he denied.
As well as Mr Bercow, Mr Corbyn is said to have nominated his former deputy Tom Watson, with whom he had a fractious working relationship, to the unelected chamber.
The reported choice of chief of staff Karie Murphy for a peerage has also been criticised, given the current inquiry into alleged instances of antisemitism in the party by the Equality and Human Rights Commission (EHRC).