Conservative MP Peter Luff, who lost his job as defence minister in yesterday's reshuffle, has announced he will stand down from Parliament at the 2015 election.
The Mid-Worcestershire MP told PA that he had decided to stand down a couple of months ago, and had waited for the reshuffle to make his announcement.
He said he was leaving the Ministry of Defence "of my own volition" after he and Prime Minister David Cameron agreed it was better to give a chance to someone who was planning to remain in Parliament beyond 2015.
Mr Luff was replaced as defence equipment minister by Philip Dunne, who entered Parliament in 2005 as MP for Ludlow.
After what will be 23 years as an MP, Mr Luff said he now wanted "to do something different for the rest of my career".
In a message to constituents, he pledged his continued loyalty to Mr Cameron and the Government.
"The coalition Government is grappling with huge challenges, the scale of which is only just becoming clear," said Mr Luff.
"David Cameron and his ministers will enjoy my robust support as they address them with the determination and energy I know they will demonstrate.
"We need to be ruthlessly focused on growth, to remain outward-looking as a country, and to work hard for fairness in all we do.
"This is the agenda of the Government and one I will do all I can to help in the future."
Mr Luff, 57, worked as an aide to former Prime Minister Edward Heath from 1977-80 and then in public relations before entering Parliament as MP for Worcester in 1992, and has represented Mid-Worcestershire since 1997.