The vote for a new leader at the council next month could see Mr Bowles ousted from his job if the person elected is in the Speechley camp.
LGC understands Mr Bowles does not want to leave the job, but the outcome of
an ongoing police investigation into Mr Speechley could sway the loyalty of his fellow members.
Mr Speechley quit his£24,000 job four months after a damning audit report accused him of unacceptable behaviour (LGC, 24 May).
Mr Speechley, who has been under pressure to resign as the authority's political head for the last 10 months, said: 'I would like to formally announce my resignation as leader of the council. I would like to thank my colleagues, members of this council and staff, who have supported me over the years.'
In a voice clearly full of emotion, Mr Speechley added: 'I wish the new leader well. I hope that person will get the same amount of support that I have had.'
But in an apparent swipe at Tory colleagues who had urged him to resign, he related a story told by Winston Churchill.
Mr Speechley said the wartime prime minister once told constituents that 'the enemy' did not sit opposite him in the House of Commons, but 'behind him'.
His Conservative colleagues, who had voted to censure him in July, listened in silence on the benches behind.
He handed his letter of resignation to council chair Graham Wheat (Con), and left.
The council elected Tory deputy leader Denis Hoyes, who represents Woodhall Spa, as its constitutional leader until an emergency meeting on 4 October.
Mr Speechley has been under police investigation since December. An ongoing inquiry involves the award of a computer contract to an IT firm which at the time had prominent local MP John Hayes on its board.