Former Prime Minister David Cameron has announced he will step down from his position in Parliament.

Cameron's unexpected announcement Monday will trigger a by-election for his seat in Oxfordshire. Cameron had earlier resigned as prime minister after failing to convince British voters in June to remain in the European Union in a referendum.

He said at the time he planned to remain in Parliament although he would no longer have a leadership role in the Conservative Party.

He has been replaced as prime minister by Theresa May, who is overseeing the process to remove Britain from the EU bloc.

Cameron had won re-election in 2015, but his position became untenable after losing the EU vote on June 23. He had campaigned in favor of remaining in the EU bloc.