Mr Miliband wants greater interaction between Labour and the public
Choosing Labour's Parliamentary candidates should no longer be the preserve of party members, says Foreign Secretary David Miliband.
In an article for Tribune, he argues US-style primary elections would give the public a greater say in selection.
He says traditional party systems are "dying" and Labour needs to improve the way it reaches out to non-members.
More than 16,000 people voted for the Tories' Totnes candidate this week in an all-postal "open primary" contest.
In an article for left-leaning Tribune magazine, Mr Miliband praises both the Greek socialist party and the US democrats for the way they involve people who are not party members in decision making.
He does not outline exactly what form of open selection he believes would work best for the party.
But he points out that the Greek party, Pasok, had allowed people to have equal rights as members or "friends" and held open primaries to select candidates for local elections.
"The traditional political structures of mainstream political parties are dying and our biggest concern is the gap between our membership and our potential voter base," he writes.
"We need to expand our reach by building social alliances and increasing opportunity for engagement and interaction with our party."
He adds: "We say we want to listen to our voters, why not a system of registered voters as in the US to create the basis for primaries?"
According to the latest party accounts figures submitted to the Electoral Commission, Labour Party membership fell for the ninth consecutive year in 2008, to 166,247 - from a peak of 405,000 in 1997.
Neal Lawson, chairman of left-wing campaign group Compass, told BBC Radio 4's Today programme that, as one of those at the top of the Labour Party over the last 10 years, Mr Miliband was among those responsible for leading it "to its death" through measures like increased privatisation.
He said "now they have almost killed it" senior Labour politicians were coming up with measures to "water down" the party even further.
"This would be the death knell of the party," he said.
"The revival of the Labour Party and the revival of British democracy will come from political parties that believe and have a vision of the good society and compete over that in fair and open democratic elections. That's what we want to see."
On Tuesday GP Dr Sarah Wollaston was named as the Conservatives' next Parliamentary candidate for Totnes in Devon, after 16,497 people voted in a selection process.
The party said the turnout exceeded its "wildest expectations" but had cost £38,000.
The Conservatives had opened up selection meetings to non-members before, but this time had gone a step further and sent all 69,000 Totnes voters a postal ballot.
In a traditional selection meeting only a few hundred party members will vote.