Chuka Umunna appeared to accidentally back David, rather than Ed, Miliband for prime minister this morning, during a combative TV interview.
Ed Miliband's leadership of the Labour Party has been under pressure over the last week. The shadow business secretary was dispatched to Sky News to dismiss the suggestion the party was heading for defeat at the election in six months time.
However the exchange with Eamon Holmes had an unfortunate end for Umunna who said the party was united in "ensuring that we get David, um, that we get Ed Miliband into No 10".
Ed narrowly beat his brother David to the Labour leadership in 2010. Umunna backed Ed in the contest and has since had a rapid rise through the party's ranks. But despite Ed having been leader for over four years, people still confuse the two brothers' names.
Labour MPs are due to gather in the Commons today for the usual meeting of the parliamentary Labour Party, amid suggestion that 20 shadow ministers are poised to call on Miliband to quit.
In an earlier interview this morning, Umunna said the media was engaged in a pointless game of "political top trumps" and that Labour was poised for victory.
He told BBC Radio 4's Today: "Yes, there have been noises off. It would be completely disingenuous of me to deny that. But it is a small minority of people, who are doing so anonymously and off the record.
"If you speak to the overwhelming majority of Labour candidates, our MPs, our supporters, people recognise this is going to be a tough election but are absolutely up for it.
"There is a lot of talk about polls, and those go up and down. But under Ed's leadership we are now within touching distance of a general election victory. We are a serious prospect for government after going down to our second worst defeat in history in 2010."
He added: "If you look at the qualities that people attribute to Ed - a man of honesty, sincerity, deep beliefs - I don't believe that those are attributes that most people give to politicians but they certainly give it to our leader.
"That is because we are focusing on the issues that actually matter to people. We are not engaged in a game of political top trumps."