Prime Minister David Cameron was poised for a ministerial reshuffle as Downing Street confirmed the resignations of two further members of the Government.
Cabinet Office Minister Chloe Smith and Deputy Chief Whip John Randall stepped down from their positions ahead of the Conservative shake-up which is expected tomorrow.
On Friday, Simon Burns quit as Transport Minister to launch a bid to be a Commons Deputy Speaker.
The departures increase the scope for Mr Cameron to bring in fresh faces to his top team - which is tipped to feature an increased number of female faces.
Ms Smith, who was only elected to the Commons in 2009 at the age of just 27 and was quickly promoted to the ministerial ranks, said she wanted the chance to "develop other ways of giving public service, both inside and outside Parliament".
As Economic Secretary to the Treasury she once suffered a humiliating verbal mauling at the hands of Newsnight presenter Jeremy Paxman over a fuel duty freeze.
The interview led to Chancellor George Osborne being branded an ''arrogant coward'' by after sending her into the TV studios to defend his decision to delay the 3p hike in fuel duty.
In her resignation letter to the Prime Minister she said she now wanted " to be able to spend more time serving my constituents".
"I was only 27 when I was lucky enough to be elected as an MP, and of my four years in Parliament so far, I have spent three as a minister.
"I would welcome the opportunity to develop other ways of giving public service, both inside and outside Parliament, while continuing to work hard for my constituents."
She said she would also take up Mr Cameron's "challenge" to find better ways to engage with young voters."
Mr Cameron applauded her "positive impact in the departments you have served" and said he looked forward to receiving her recommendations on encouraging young people to vote.
"As you know from our previous conversations, this is a topic I take seriously and believe that there is scope for action," he told her.
Mr Randall, 58, has been the Conservative MP for Uxbridge and South Ruislip since a 1997 by-election and told the Prime Minister at the end of last year that he wished to step down.
He said it had been "a great privilege and honour" to serve for 13 years in the Whips' Office in opposition and Government.
"I have nothing but the deepest admiration for you as a person, leader and Prime Minister. I will never forget the kind note that you wrote to me when my mother died last year," he said.
"You can be assured that I will do whatever I can for you personally as well as for the party, the Government and of course the country."
The Prime Minister said he "could not have wished for a more loyal, discreet, patient, trustworthy and committed colleague" and that he "had rather hoped this day would never come".
"You have been a rock, not just in the Whips Office since 2000 where you have served with great distinction as Assistant and then Deputy Chief Whip, but for the whole Parliamentary Party.
"Your wit and humour are well known across the Party, but so too is your compassion; your dedication to the Party and to Parliament; and your steadfast reliability in good times and bad."