Tony Blair rarely gets involved with Britain's Labour these days but the risk his party could pick an old-fashioned left-winger as leader prompted him to do so Wednesday, as his legacy looms over the contest.
While still vilified by many for leading Britain into the Iraq war from 2003, Blair is Labour's longest-serving prime minister and believes the party would not be electable if it picks Jeremy Corbyn as its next leader.
There are signs it could be about to do so, as other candidates have struggled to make an impact outside Westminster.
A new YouGov/Times opinion poll has put the bearded Corbyn, whose views one colleague said were the closest thing Britain had to those of Greece's hard-left Syriza, ahead of his three rivals.
Labour will announce its new leader on September 12 after Ed Miliband stepped down in May.
He quit in the wake of a crushing election defeat by Prime Minister David Cameron's Conservatives which notably saw Labour lose all but one of its seats in Scotland, a former heartland.
Blair and Corbyn could hardly be more different.
Blair, prime minister for 10 years from 1997, devoted his career to dragging Labour to the centre ground.
"When people say my heart says I should really be with that (leftwing) politics -- well, get a transplant, because that's just dumb," Blair, tanned and in an open-neck shirt and dark suit, told a packed meeting of Labour supporters in London.
"You win from the centre, you win when you appeal to a broad cross section of the public, you win when you support business as well as unions. You don't win from a traditional leftist platform."
Nicknamed "Comrade Corbyn" by the press, the 66-year-old backbench lawmaker, who usually wears a worn beige jacket and slacks, opposes austerity measures, was a vocal campaigner against the Iraq war and wants to scrap Britain's nuclear weapons.
Labour in 'emotional trauma' -
Most Labour insiders believe it is unlikely Corbyn will actually win the leadership race, particularly amid questions over the reliability of polls after their failure to predict May's election result.
Bookmakers Ladbrokes make Andy Burnham, a slick former minister under Blair and Gordon Brown who has tacked to the left in recent years, favourite to win at 6/5, with Corbyn second at 2/1.
But it is clear that he has caught the imagination of many Labour members and supporters thanks to his clearly expressed, traditional left-wing policies.
These contrast with what some Labour supporters now see as the compromises of the Blair years which they say took the party too far away from its socialist roots.
The split in thinking between left-wingers and centrists was highlighted this week when 48 Labour lawmakers defied the party's interim leadership to vote against planned government cuts to welfare.
Professor Mark Wickham-Jones of Bristol University told AFP Corbyn was appealing "because there is a substantial segment of the party that's no longer interested in any kind of strategy that revolves around deficit management, austerity".
"There's a post-Blairite generation coming in that don't believe in Corbyn as a candidate but do believe in him as an idea," he added.
Another of Blair's former ministers, David Blunkett, explained Corbyn's unexpected popularity by saying that Labour was still "in emotional trauma" following the heavier than expected election defeat.
With Britain's political class starting its summer recess this week, commentators say Labour must consider whether it wants to be simply a principled opposition or a party with a real shot at power at the next general election in 2020.
The Observer, the Sunday newspaper traditionally closest to Labour, said in an editorial this week: "The problem isnât just Corbyn, since none in the leadership election inspires real confidence". afp