The news came shortly before Ms Rudd was told she would not be readmitted to the Conservative party after walking out of Boris Johnson’s cabinet and resigning the Tory whip last month in protest at the expulsion of 21 fellow Tories for rebelling against a no-deal Brexit.
She was not one of the 10 MPs invited back into the Tory fold on Tuesday as Mr Johnson sought to prepare the ground for the 12 December election.
And in a letter, chief whip Mark Spencer told her: “The receipt of the whip is an honour not a right and as such it cannot be discarded or returned at will if it is to have any meaning.”
Mr Spencer indicated that he feared Ms Rudd would undermine Mr Johnson if she was allowed back into the party, telling her that at the time she resigned, “you were clear that you did not support the approach of the prime minister and did not have confidence in him. You have failed to provide me with reassurances that you will not change your mind once more”.
The refusal of the whip came as a surprise to the Hastings and Rye MP, who responded: “Funny thing really, as just last week the PM asked me to stand in the general election.”
Ms Rudd said that she had had a “good meeting” with the PM just a few days ago and was “really confident of my position”.
The 56-year-old independent MP – once tipped as a future prime minister – made clear that the decision to leave the Commons did not mark the end of her political ambitions.
Announcing her decision to step down, she told the Evening Standard: “I’m not finished with politics, I’m just not standing at this election.”
Ms Rudd – who had previously indicated she could leave her hyper-marginal constituency and fight a London seat as an independent – did not rule out a return to the Commons in future but said there were “many other things I want to do”.
Ms Rudd said it was “difficult” to quit the cabinet, but said she did it out of “solidarity” with colleagues whose Conservative values she shared and respected.
She said she was pleased that Mr Johnson had now invited some of them back into the party and allowed them to stand as Tories at the election.
But she added: “I’m just very pleased the party appears to be reasserting itself, although it’s disappointing it does not include a few of them.”
Among those expelled last month who have not yet had the whip returned are her former cabinet colleagues Philip Hammond, Oliver Letwin and David Gauke.
Investment banker Ms Rudd entered parliament in 2010 as part of the socially liberal wave of Tories fostered by David Cameron, and was soon promoted to ministerial rank, joining the cabinet as energy secretary following the 2015 election.
She campaigned for Remain in the 2016 EU referendum, famously telling a live TV debate that Mr Johnson “is the life and soul of the party, but he isn’t the man you want driving you home at the end of the evening”.
She was sent to stand in for Theresa May in a TV debate in the 2017 general election when the then prime minister refused to face other party leaders.
May had appointed her home secretary on her election as Tory leader, but her stint was cut short in 2018 when she resigned after admitting misleading a parliamentary committee about the deportation of members of the Windrush generation.
She was restored to the cabinet as work and pensions secretary in November last year and stayed on in the post under Mr Johnson, who also made her minister for women and equalities.
Also announcing plans to stand down from parliament at the election were Aylesbury MP and former justice secretary David Lidington, who was Theresa May’s effective deputy for 18 months until her departure in July this year, and Derbyshire Dales MP Sir Patrick McLoughlin, 61, who served as transport secretary from 2012-16 and Conservative party chair from 2016-18.
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