Mahmood has demanded that Mike Tapp, the minister for migration and citizenship, be sacked for writing an unauthorised newspaper article calling for overseas care workers to be exempted from tougher settlement rules.
But No 10 has so far declined to sack Tapp, saying no decision has been made by the prime minister, the report added.
Tapp wrote in the Times that it was his "strong belief" that migrant care workers should not have to wait longer to settle permanently in Britain.
"Those who have come to the United Kingdom on care worker visas who have played by the rules and have genuinely contributed to our care system should not be required to wait longer to apply for settlement. That is the issue I am working hard to address," he wrote.
Mahmood was unaware Tapp had written the article, the Guardian reported, citing a source close to her. "Mike Tapp is expected to be sacked for breaching the ministerial code. He has taken possible ideas that the home secretary and her team were working on, and briefed them as his own to try to win a job in the new administration," the source said.
Downing Street said it was up to the prime minister to judge ministerial conduct, the report added.
'Country above party politics'
Tapp hit back, telling the Times he "won't be intimidated". He said Mahmood's position had shifted from accusing him of breaking the ministerial code to claiming "he stole my idea".
In a social media post, he wrote: "I have put my views across on a policy I've been working on for months (I have the receipts) in an Op Ed in the Times. Give it a read, and let's continue to discuss. I won't be intimidated to drop my views. Stay classy!" He added: "I'm adamant that we must always put country above party politics and I will continue to do so."
Jake Richards, a junior justice minister, told Times Radio that the Home Office should "take a deep breath" over the row, saying Tapp had been "exploring ideas" and that doing so publicly was "unwise".
Mike Tapp speaks during an event to launch Labour's election pledges at The Backstage Centre on May 16, 2024 in Purfleet, United Kingdom. (Photo by Leon Neal/Getty Images)
The row comes as Labour figures jostle for roles ahead of Andy Burnham's expected takeover as prime minister, possibly as early as July 17.
Burnham criticised retrospective application
Burnham has previously criticised retrospective application of the settlement changes, saying they leave migrants "in a sense of limbo".
Mahmood announced in November plans to double the wait for indefinite leave to remain from five to ten years for most migrants, with transitional arrangements for an estimated 1.6 million people who arrived since 2021. More than 100 Labour MPs have written to her urging that the changes not apply retrospectively.
According to Home Office data, 616,266 health and care visas were issued between 2022 and 2024, more than half of them to dependants. About 200,000 care workers and their dependants are expected to apply for permanent settlement by 2030 if the five-year rule remains unchanged.
Shadow home secretary Chris Philp accused the government of descending "into chaos and infighting", saying Tapp had openly defied Mahmood "in a brazen attempt to get a place in Burnham's cabinet".
"There is not a single thought for the national interest here. All these Labour ministers care about is their own personal ambition and jockeying for government jobs. It's beneath contempt," Philp was quoted as saying by the Guardian.
