One of Gordon Brown's closest allies has described David Miliband's call for US-style primaries as "idiotic".
The Foreign Secretary caused consternation by saying Labour should follow the Tories' move in Totnes by selecting candidates in an open primary system.
Tom Watson, the former Cabinet Office minister who remains close to the Prime Minister, used Twitter to condemn the idea.
He told David Lammy, the education minister: "They're an idiotic notion. They price the poor out of representation. Don't want US-style politics in the UK thank you v much."
Mr Lammy replied: "Not idiotic, adds to the renewal debate, not pricing poor out of politics, aims to bring spirit of New Hampshire Primary to London."
In an article for Tribune, Mr Miliband said people could register as "friends" of Labour to take part in selection contests.
Sarah Wollaston, a GP with no political experience, was selected as Totnes's Tory candidate by a postal ballot of voters last week.