Former UK Prime Minister David Cameron is to stand down as an MP, triggering a by-election in his Oxfordshire seat of Witney.
Cameron, who resigned as prime minister after June's EU referendum, said he did not want to be a "distraction" for new PM Theresa May, according to BBC report.
He had said he would continue as an MP until the next general election.
The 49-year-old, who has represented Witney since 2001, became Conservative leader in 2005 and PM in 2010.
Speaking in his constituency, he said it had been a "great honour" to be an MP for the area, but said it would be difficult for him to remain on the backbenches without becoming "a big distraction and a big diversion" from the work of the new government.
He denied his announcement was related to the government's moves towards allowing new grammar schools, a policy he rejected as PM.
He said the timing - which came after a period of reflection over the summer - was coincidental, adding that there were "many good things" in the proposed education reforms.