Conservative MP Andrew Tyrie, who chairs the powerful Treasury Select Committee, is to stand down from Parliament at the general election.
The MP, who has represented Chichester in Sussex since 1997, said at the age of 60 it was time to do other things but he was committed to public service.
Mr Tyrie, who worked for BP before entering politics, has led the Treasury committee since 2010.
Veteran Tory MP Sir Alan Haselhurst is also quitting after 40 years.
Sir Alan, who has held the Essex seat of Saffron Walden since 1977, initially intended to contest the seat again on 8 June.
But, in a statement on Tuesday, the 79-year old said he had changed his mind after consulting with his family and close friends.
"When I heard the prime minister's announcement of an early general election I reacted enthusiastically with my only thought being to play my part in strengthening the position of the Conservative Party in Parliament," he said.
"I feel now that my initial instinctive response was premature...
"Whilst I have no doubt as to my capacity and commitment to carry out my representative duties I have begun to recognize that it might test the friendship and goodwill of so many people whose support I have enjoyed if I sought to do so for a further five years."
Sir Alan, who was first elected to Parliament in 1970 for Middleton and Prestwich and was deputy Commons speaker between 1997 and 2010, has faced opposition to his candidacy from within his local party.
In his resignation letter, Mr Tyrie - who opposed Brexit - said he was proud of his contribution to strengthening the select committee system and making Parliament more relevant.
Known for his forensic, and at times, acerbic style, Mr Tyrie clashed with then Prime Minister David Cameron on several occasions in his capacity as chairman of the liaison committee of senior backbenchers.
He also served as chairman of the all-party parliamentary group on extraordinary rendition, in addition to his Treasury committee duties.
"I remain deeply committed to public service," he said. "I am determined, and hopefully young enough, to contribute in other ways in the years ahead."