Priti Patel has announced she will be not standing to succeed Boris Johnson as Prime Minister after days of deliberating.
The Home Secretary said in a statement she had decided not to put herself forward - but declined to say who she was backing.
Ms Patel, who is known for her hardline stance on immigration and who has championed plans to deport asylum seekers to Rwanda, had reportedly hoped to unite the right of the party behind her.
She is understood to have told fellow MPs that she was the "best placed" Brexiteer candidate to win the next General Election.
But she appears to have shelved her leadership hopes amid fears she could split the right of the party after fraught meetings with fellow MPs.
She said: "I am grateful for the encouragement and support colleagues and Party members have offered me in recent days in suggesting that I enter the contest for the leadership of the Conservative Party.
"I will not be putting my name forward for the ballot of MPs."
The Home Secretary continued: "Like all Conservative MPs and Party members, I will be listening to cases being put forward by the candidates standing for the leadership of the Party and trust the contest will be conducted in a good spirit that brings our Party together."
Before announcing she would not be standing she had the public backing of 11 MPs, with Home Office ministers Kevin Foster and Tom Pursglove among them.
She said she would continue to focus on her duties as Home Secretary.
It came hours after Ms Patel was telling Brexiteer Tories she was the only right-winger who could win the next election.
Leading Brexiteer Penny Mordaunt topped a poll of party members despite hardliners’ claims she was too “woke” for the top job.
Newcomer Kemi Badenoch was snapping at her heels but Tory critics suggested she lacked the experience or gravitas for No 10.
Attorney General Suella Braverman, the current favourite among pro-Brexit hardliner MPs, dispatched lieutenants to warn the contest was too crowded.
One Tory Brexiteer told the Mirror: "It's a nightmare.”
Ms Patel, 50, has been a key part of Mr Johnson's government - and one of his staunchest supporters - since her appointment in 2019.
The Prime Minister made the surprise move to resurrect her ministerial career in 2019, following her high profile sacking by his predecessor, Theresa May, two years earlier.
Ms Patel was forced out from her role as international development minister under May following a scandal over unauthorised meetings with the Israeli government that breached the ministerial code.
She was again accused of breaking the Code over bullying claims but exonerated by Boris Johnson, who overturned an ethics advisor's recommendation in 2020.
Throughout the Partygate scandal she said Johnson had her full support, and was not among the wave of ministers to quit as the PM's leadership crumbled last week.
The Home Secretary showed her loyalty to Boris Johnson by chivvying MPs on a Tory WhatsApp group that they needed to get behind him.
She is understood to have met with Tories from the European Research Group (ERG) to garner support for her leadership run.
