Nick Clegg and Chris Huhne: How similar are they?
It is striking - within a party that's generally regarded as nice - how nasty the Liberal Democrats are quietly capable of being.
By Guto Harri
BBC political correspondent
The two candidates, now competing to lead the party have the kind of breeding and education that leads to public restraint, but the tension between them was easily detectable at a central London hustings last night.
Personal relationships are often more hostile within parties than between them, but it is odd to sense the animosity between Clegg and Huhne
"That's barking" said Chris Huhne of Nick Clegg's view of the Trident nuclear weapons system.
"Sorry... I don't understand," said Clegg about his rival's proposal to scrap it, faking miscomprehension to project a polite attack on what he regards as illogical, unwise and incoherent.
It was not hard to guess who "David Cameron's body double" was meant to be. Or the "heir to Blair" that the party was warned against by Chris Huhne.
And you could read "only I" into almost every sentence by Clegg, the self-assured 40-year-old home affairs spokesman explaining what could be achieved by the party under the right leader.
Personal relationships are often more hostile within parties than between them, but it is odd to sense the animosity between Clegg and Huhne. Their backgrounds are not only similar... they are almost identical.
They both went to the same public school, Westminster. They are both Oxbridge graduates. Both trained as financial journalists. Both served in the European Parliament and they arrived at the House of Commons as part of the new 2005 Lib Dem intake.
They even share a passion for southern European women. One married a Spanish woman. The other a Greek.
JOB: Environment spokesman
FAMILY: Married, five children
EDUCATION: Westminster School, Oxford University
BEFORE MP: Journalist, businessman and Euro MP
Yet, beyond that template there are differences, and the contest is already bringing them out.
His manifesto mugshot shows a smiling Chris Huhne in a baby blue shirt with an open neck. The man who launched that document wore a sober suit, dull tie, mandatory poppy and straight face.
He described himself as anti-establishment, but his credentials suggest the opposite. Parents these days spend £8,652 a term to send their sons to the central London school where he studied as a child. He made a ton of money, and owns a fair few homes.
His rebellion - as he sees it - was setting up a business, building it up from scratch, taking risks and gaining experience of what he referred to many times as "the real world".
He contrasted that with David Cameron and Gordon Brown - both career politicians, though they both spent a little time in television.
He clearly puts Nick Clegg in the same camp, though his dismissal of his rival was more subtle.
Nick, he pointed out, trained as a journalist, but he (Chris) worked as one. Nick worked in the public sector (the European Commission). He made it in the private arena.
But what choice do the 70,000 Liberal Democrat members who will vote between November 21 and mid-December really have?
Nick Clegg is younger and there's nothing 53-year-old Chris Huhne can do to close that gap. But the older man invites audiences to notice his grey hairs. Experience - as he sees it - is an advantage.
Clegg's previous conviction for arson suggest he has an edge in the anti-establishment stakes, but years have passed since he torched the precious plants of an angry German.
JOB: Home Affairs spokesman
FAMILY: Married, two children
EDUCATION: Westminster School, Cambridge University
BEFORE MP: Journalist, lecturer and Euro MP
Huhne can not invent a night in the cells, but articles from his student days reportedly suggest an early very liberal attitude to drugs. He has also matched his young rival's more recent promise to break the law. Both are now committed to lead a campaign of civil disobedience against identity cards, going to court and prison if necessary.
Other than that, their party hustings will provide a search for nuances, emphases, and mood music.
Even their differences on Trident will not matter much until 2010 when a final decision has to be taken.
That - in the recent life of all leaders of British opposition parties - is a long way off.