Shadow business secretary Chuka Umunna has withdrawn from the Labour party leadership contest, he has announced.
Mr Umunna, 36, had been the second candidate to declare his intention to stand, via a post on his Facebook page.
But he said in a statement that he was not comfortable with the level of pressure that came with being a leadership candidate.
A rising star of the party, Mr Umunna was first elected to Parliament in 2010 before joining the shadow cabinet.
Yvette Cooper, Andy Burnham, Liz Kendall and Mary Creagh have already thrown their hats into the ring for the Labour top job.
Candidates must secure nominations from 34 colleagues - 15% of the party's MPs - by 15 June to make it on to ballot papers, which will be sent to members in August ahead of the leader's election a month later.
Mr Umunna confirmed his candidacy on 12 May, saying Labour under Ed Miliband had failed to appeal to enough voters in England.
But in a statement on Friday he announced his intention to withdraw from the race.
He said he though he understood "the scrutiny and attention a leadership contest would bring", but added: "However, since the night of our defeat last week I have been subject to the added level of pressure that comes with being a leadership candidate.
"I have not found it to be a comfortable experience."
He added: "One can imagine what running for leader can be like, understand its demands and the attention but nothing compares to actually doing it and the impact on the rest of one's life.
"Consequently after further reflection I am withdrawing my candidacy."
The shadow business secretary said he had wondered if it was too soon for him to stand for the leadership, adding: "I fear it was."
He also cited concerns about the impact on those close to him.
Mr Umunna said he would continue to serve as shadow business secretary and hoped to "play a leading role" in Labour's campaign to keep the UK in the EU during the forthcoming in/out referendum.